diff --git a/checks/class-file-check.php b/checks/class-file-check.php
index 90607752..f0fce6c1 100644
--- a/checks/class-file-check.php
+++ b/checks/class-file-check.php
@@ -66,7 +66,7 @@ public function check( $php_files, $css_files, $other_files ) {
 			'favicon\.ico'        => __( 'Favicon', 'theme-check' ),
 		);
 
-		$musthave = array( 'index.php', 'style.css', 'readme.txt' );
+		$musthave = array( 'index.php', 'style.css' );
 
 		checkcount();
 
diff --git a/checks/class-readme-check.php b/checks/class-readme-check.php
new file mode 100644
index 00000000..99bf0a43
--- /dev/null
+++ b/checks/class-readme-check.php
@@ -0,0 +1,285 @@
+<?php
+/**
+ * Validate readme files.
+ *
+ * @link https://meta.svn.wordpress.org/sites/trunk/wordpress.org/public_html/wp-content/plugins/plugin-directory/readme/
+ *
+ * @package Theme Check
+ */
+
+class Readme_Check implements themecheck {
+
+	/**
+	 * Error messages, warnings and info notices.
+	 *
+	 * @var array $error
+	 */
+	protected $error = array();
+
+	/**
+	 * Theme information. Author URI, theme URI, Author name
+	 *
+	 * @var object $theme
+	 */
+	protected $theme;
+
+	/**
+	 * Theme slug.
+	 *
+	 * @var object $slug
+	 */
+	protected $slug;
+
+	function set_context( $data ) {
+		if ( isset( $data['theme'] ) ) {
+			$this->theme = $data['theme'];
+		}
+		if ( isset( $data['slug'] ) ) {
+			$this->slug = $data['slug'];
+		}
+	}
+
+	/**
+	 * Check that return true for good/okay/acceptable, false for bad/not-okay/unacceptable.
+	 *
+	 * @param array $php_files File paths and content for PHP files.
+	 * @param array $css_files File paths and content for CSS files.
+	 * @param array $other_files Folder names, file paths and content for other files.
+	 */
+	public function check( $php_files, $css_files, $other_files ) {
+
+		/**
+		 * Latest WordPress version
+		 *
+		 * @var string $latest_wordpress_version
+		 */
+		if ( defined( 'WP_CORE_LATEST_RELEASE' ) ) {
+			// When running on WordPress.org, this constant defines the latest WordPress release.
+			$latest_wordpress_version = WP_CORE_LATEST_RELEASE;
+		} else {
+			// Assume that the local environment being tested in is up to date.
+			$latest_wordpress_version = $GLOBALS['wp_version'];
+		}
+
+		checkcount();
+
+		// Get a list of file names and check for the readme.
+		$readme = '';
+
+		// Get the contents of themeslug/filename:
+		foreach ( $other_files as $path => $contents ) {
+			if ( stripos( $path, $this->slug . '/readme.txt' ) || stripos( $path, $this->slug . '/readme.md' ) !== false ) {
+				$readme .= $contents;
+			}
+		}
+
+		// Publish an error if there is no readme file.
+		if ( empty( $readme ) ) {
+			$this->error[] = sprintf(
+				'<span class="tc-lead tc-required">%s</span>: %s',
+				__( 'REQUIRED', 'theme-check' ),
+				__( 'The readme file is missing.', 'theme-check' )
+			);
+			$ret           = false;
+		} else {
+			// Parse the content of the readme.
+			$readme = new Readme_Parser( $readme );
+
+			// Error if the theme name is missing in the readme.
+			if ( empty( $readme->name ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-required">%s</span>: %s',
+					__( 'README ERROR', 'theme-check' ),
+					/* translators: 1: 'Theme Name' section title, 2: 'Theme Name' */
+					sprintf(
+						__( 'Could not find a theme name in the readme. Theme name format looks like: %1$s. Please change %2$s to reflect the actual name of your theme.', 'theme-check' ),
+						'<code>=== Theme Name ===</code>',
+						'<code>Theme Name</code>'
+					)
+				);
+				$ret = false;
+			} elseif ( $readme->name != $this->theme ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-required">%s</span>: %s',
+					__( 'README ERROR', 'theme-check' ),
+					/* translators: 1: actual theme name, 2: theme name in readme, 3: 'Theme Name' section title, 4: 'Theme Name' */
+					sprintf(
+						__( 'The theme name in the readme %1$s does not match the name of your theme %2$s. Theme name format looks like: %3$s. Please change %4$s to reflect the actual name of your theme.', 'theme-check' ),
+						'<code>' . esc_html( $readme->name ) . '</code>',
+						'<code>' . esc_html( $this->theme ) . '</code>',
+						'<code>=== Theme Name ===</code>',
+						'<code>Theme Name</code>'
+					)
+				);
+				$ret = false;
+			}
+
+			// Warnings.
+			if ( isset( $readme->warnings['requires_header_ignored'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					/* translators: 1: theme header tag; 2: Example version 5.0. 3: Example version 4.9. */
+					sprintf(
+						__( 'The %1$s field in the readme was ignored. This field should only contain a valid WordPress version such as %2$s or %3$s.', 'theme-check' ),
+						'<code>Requires at least</code>',
+						'<code>' . number_format( $latest_wordpress_version, 1 ) . '</code>',
+						'<code>' . number_format( $latest_wordpress_version - 0.1, 1 ) . '</code>'
+					)
+				);
+			} elseif ( empty( $readme->requires ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: theme header tag */
+						__( 'The %s field is missing from the readme.', 'theme-check' ),
+						'<code>Requires at least</code>'
+					)
+				);
+			}
+
+			if ( isset( $readme->warnings['tested_header_ignored'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: 1: theme header tag; 2: Example version 5.0. 3: Example version 5.1. */
+						__( 'The %1$s field in the readme was ignored. This field should only contain a valid WordPress version such as %2$s or %3$s.', 'theme-check' ),
+						'<code>Tested up to</code>',
+						'<code>' . number_format( $latest_wordpress_version, 1 ) . '</code>',
+						'<code>' . number_format( $latest_wordpress_version + 0.1, 1 ) . '</code>'
+					)
+				);
+			} elseif ( empty( $readme->tested ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: plugin header tag */
+						__( 'The %s field is missing from the readme.', 'theme-check' ),
+						'<code>Tested up to</code>'
+					)
+				);
+			}
+
+			if ( isset( $readme->warnings['requires_php_header_ignored'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: 1: plugin header tag; 2: Example version 5.2.4. 3: Example version 7.0. */
+						__( 'The %1$s field in the readme was ignored. This field should only contain a PHP version such as %2$s or %3$s.', 'theme-check' ),
+						'<code>Requires PHP</code>',
+						'<code>5.2.4</code>',
+						'<code>7.0</code>'
+					)
+				);
+			} elseif ( empty( $readme->requires_php ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: plugin header tag */
+						__( 'The %s field is missing from the readme.', 'theme-check' ),
+						'<code>Requires PHP</code>'
+					)
+				);
+			}
+
+			if ( 2 <= count( $readme->contributors ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: theme header tag */
+						__( 'The %s field should only contain one WordPress.org username. Remember that usernames are case-sensitive.', 'theme-check' ),
+						'<code>Contributors</code>'
+					)
+				);
+			} elseif ( ! count( $readme->contributors ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: theme header tag */
+						__( 'The %s field is missing from the readme or is empty.', 'theme-check' ),
+						'<code>Contributors</code>'
+					)
+				);
+			}
+
+			if ( empty( $readme->license ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: theme header tag */
+						__( 'The %s field is missing from the readme.', 'theme-check' ),
+						'<code>License</code>'
+					)
+				);
+			}
+
+			if ( empty( $readme->license_uri ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-warning">%s</span>: %s',
+					__( 'README WARNING', 'theme-check' ),
+					sprintf(
+						/* translators: %s: theme header tag */
+						__( 'The %s field is missing from the readme.', 'theme-check' ),
+						'<code>License URI</code>'
+					)
+				);
+			}
+
+			// Info.
+			if ( empty( $readme->sections['description'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-info ">%s</span>: %s',
+					__( 'README INFO', 'theme-check' ),
+					sprintf(
+						/* translators: %s: section title */
+						__( 'No %s section was found in the readme.', 'theme-check' ),
+						'<code>== Description ==</code>'
+					)
+				);
+			}
+
+			if ( empty( $readme->sections['faq'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-info ">%s</span>: %s',
+					__( 'README INFO', 'theme-check' ),
+					sprintf(
+						/* translators: %s: section title */
+						__( 'No %s section was found in the readme.', 'theme-check' ),
+						'<code>== Frequently Asked Questions ==</code>'
+					)
+				);
+			}
+
+			if ( empty( $readme->sections['changelog'] ) ) {
+				$this->error[] = sprintf(
+					'<span class="tc-lead tc-info ">%s</span>: %s',
+					__( 'README INFO', 'theme-check' ),
+					sprintf(
+						/* translators: %s: section title */
+						__( 'No %s section was found in the readme.', 'theme-check' ),
+						'<code>== Changelog ==</code>'
+					)
+				);
+			}
+		}
+	}
+
+	/**
+	 * Get error messages from the checks.
+	 *
+	 * @return array Error message.
+	 */
+	public function getError() {
+		return $this->error;
+	}
+}
+
+$themechecks[] = new Readme_Check();
diff --git a/checks/class-readme-parser.php b/checks/class-readme-parser.php
new file mode 100644
index 00000000..e10b3c23
--- /dev/null
+++ b/checks/class-readme-parser.php
@@ -0,0 +1,408 @@
+<?php
+/**
+ * Readme Parser.
+ *
+ * @package Theme Check
+ */
+class Readme_Parser {
+
+	/**
+	 * Theme name
+	 *
+	 * @var string
+	 */
+	public $name = '';
+
+	/**
+	 * Theme tags
+	 *
+	 * @var array
+	 */
+	public $tags = array();
+
+	/**
+	 * Minimum WordPress version
+	 *
+	 * @var string
+	 */
+	public $requires = '';
+
+	/**
+	 * Tested up to
+	 *
+	 * @var string
+	 */
+	public $tested = '';
+
+	/**
+	 * Requires PHP
+	 *
+	 * @var string
+	 */
+	public $requires_php = '';
+
+	/**
+	 * Contributors, a WordPress.org username.
+	 *
+	 * @var array
+	 */
+	public $contributors = array();
+
+	/**
+	 * Donation link
+	 *
+	 * @var string
+	 */
+	public $donate_link = '';
+
+	/**
+	 * Readme short description
+	 *
+	 * @var string
+	 */
+	public $short_description = '';
+
+	/**
+	 * Theme license
+	 *
+	 * @var string
+	 */
+	public $license = '';
+
+	/**
+	 * Theme license URI
+	 *
+	 * @var string
+	 */
+	public $license_uri = '';
+
+	/**
+	 * Readme sections
+	 *
+	 * @var array
+	 */
+	public $sections = array();
+
+	/**
+	 * Theme upgrade notice
+	 *
+	 * @var array
+	 */
+	public $upgrade_notice = array();
+
+	/**
+	 * Theme FAQ
+	 *
+	 * @var array
+	 */
+	public $faq = array();
+
+	/**
+	 * Warning flags which indicate specific parsing failures have occured.
+	 *
+	 * @var array
+	 */
+	public $warnings = array();
+
+	/**
+	 * These are the readme sections that we expect.
+	 *
+	 * @var array
+	 */
+	private $expected_sections = array(
+		'description',
+		'installation',
+		'faq',
+		'changelog',
+		'upgrade_notice',
+		'other_notes',
+	);
+
+	/**
+	 * We alias these sections, from => to
+	 *
+	 * @var array
+	 */
+	private $alias_sections = array(
+		'frequently_asked_questions' => 'faq',
+		'change_log'                 => 'changelog',
+	);
+
+	/**
+	 * These are the valid header mappings for the header.
+	 *
+	 * @var array
+	 */
+	private $valid_headers = array(
+		'tested'            => 'tested',
+		'tested up to'      => 'tested',
+		'requires'          => 'requires',
+		'requires at least' => 'requires',
+		'requires php'      => 'requires_php',
+		'tags'              => 'tags',
+		'contributors'      => 'contributors',
+		'donate link'       => 'donate_link',
+		'license'           => 'license',
+		'license uri'       => 'license_uri',
+	);
+
+	/**
+	 * Parser constructor.
+	 *
+	 * @param string $string Contents of a readme to parse.
+	 */
+	public function __construct( $string ) {
+		$this->parse_readme_contents( $string );
+	}
+
+	/**
+	 * Parse and sanitize the readme
+	 *
+	 * @param string $contents The contents of the readme to parse.
+	 * @return bool
+	 */
+	protected function parse_readme_contents( $contents ) {
+		if ( preg_match( '!!u', $contents ) ) {
+			$contents = preg_split( '!\R!u', $contents );
+		} else {
+			$contents = preg_split( '!\R!', $contents ); // regex failed due to invalid UTF8 in $contents, see #2298
+		}
+		// Remove empty lines.
+		$contents = array_map( array( $this, 'strip_newlines' ), $contents );
+
+		// Strip UTF8 BOM if present.
+		if ( 0 === strpos( $contents[0], "\xEF\xBB\xBF" ) ) {
+			$contents[0] = substr( $contents[0], 3 );
+		}
+
+		// Convert UTF-16 files.
+		if ( 0 === strpos( $contents[0], "\xFF\xFE" ) ) {
+			foreach ( $contents as $i => $line ) {
+				$contents[ $i ] = mb_convert_encoding( $line, 'UTF-8', 'UTF-16' );
+			}
+		}
+
+		$contents = array_filter( $contents, 'strlen' );
+
+		$line       = $this->get_first_nonwhitespace( $contents );
+		$this->name = $this->sanitize_text( trim( $line, "#= \t\0\x0B" ) );
+
+		// Strip Github style header\n==== underlines.
+		if ( ! empty( $contents ) && '' === trim( $contents[0], '=-' ) ) {
+			array_shift( $contents );
+		}
+
+		// Handle readme's which do `=== Theme Name ===\nMy SuperAwesome Name\n...`
+		if ( 'theme name' == strtolower( $this->name ) ) {
+
+			$line       = $this->get_first_nonwhitespace( $contents );
+			$this->name = $line;
+
+			// Ensure that the line read wasn't an actual header or description.
+			if ( strlen( $line ) > 50 || preg_match( '~^(' . implode( '|', array_keys( $this->valid_headers ) ) . ')\s*:~i', $line ) ) {
+				$this->name = false;
+				array_unshift( $contents, $line );
+			}
+		}
+
+		// Parse headers.
+		$headers = array();
+
+		$line = $this->get_first_nonwhitespace( $contents );
+		do {
+			$value = null;
+			if ( false === strpos( $line, ':' ) ) {
+
+				// Some themes have line-breaks within the headers.
+				if ( empty( $line ) ) {
+					break;
+				} else {
+					continue;
+				}
+			}
+
+			$bits                = explode( ':', trim( $line ), 2 );
+			list( $key, $value ) = $bits;
+			$key                 = strtolower( trim( $key, " \t*-\r\n" ) );
+			if ( isset( $this->valid_headers[ $key ] ) ) {
+				$headers[ $this->valid_headers[ $key ] ] = trim( $value );
+			}
+		} while ( ( $line = array_shift( $contents ) ) !== null );
+		array_unshift( $contents, $line );
+
+		if ( ! empty( $headers['requires'] ) ) {
+			$this->requires = $this->sanitize_requires_version( $headers['requires'] );
+		}
+		if ( ! empty( $headers['tested'] ) ) {
+			$this->tested = $this->sanitize_tested_version( $headers['tested'] );
+		}
+		if ( ! empty( $headers['requires_php'] ) ) {
+			$this->requires_php = $this->sanitize_requires_php( $headers['requires_php'] );
+		}
+		if ( ! empty( $headers['contributors'] ) ) {
+			$this->contributors = explode( ',', $headers['contributors'] );
+			$this->contributors = array_map( 'trim', $this->contributors );
+		}
+		if ( ! empty( $headers['license'] ) ) {
+			// Handle the many cases of "License: GPLv2 - http://..."
+			if ( empty( $headers['license_uri'] ) && preg_match( '!(https?://\S+)!i', $headers['license'], $url ) ) {
+				$headers['license_uri'] = $url[1];
+				$headers['license']     = trim( str_replace( $url[1], '', $headers['license'] ), " -*\t\n\r\n" );
+			}
+			$this->license = $headers['license'];
+		}
+		if ( ! empty( $headers['license_uri'] ) ) {
+			$this->license_uri = $headers['license_uri'];
+		}
+
+		return true;
+	}
+
+	/**
+	 * Get the first non white space in the readme file content
+	 *
+	 * @access protected
+	 *
+	 * @param string $contents Readme file content.
+	 * @return string
+	 */
+	protected function get_first_nonwhitespace( &$contents ) {
+		while ( ( $line = array_shift( $contents ) ) !== null ) {
+			$trimmed = trim( $line );
+			if ( ! empty( $trimmed ) ) {
+				break;
+			}
+		}
+
+		return $line;
+	}
+
+	/**
+	 * Strip new lines
+	 *
+	 * @access protected
+	 *
+	 * @param string $line The line to remove the line endings from.
+	 * @return string
+	 */
+	protected function strip_newlines( $line ) {
+		return rtrim( $line, "\r\n" );
+	}
+
+	/**
+	 * Sanitize and remove characters from the theme name
+	 *
+	 * @access protected
+	 *
+	 * @param string $text Text to sanitize.
+	 * @return string
+	 */
+	protected function sanitize_text( $text ) {
+		$text = wp_strip_all_tags( $text );
+		$text = esc_html( $text );
+		$text = trim( $text );
+
+		return $text;
+	}
+
+	/**
+	 * Sanitizes the Requires PHP header to ensure that it's a valid version header
+	 *
+	 * @param string $version Minimum required PHP version.
+	 * @return string The sanitized $version
+	 */
+	protected function sanitize_requires_php( $version ) {
+		$version = trim( $version );
+
+		// x.y or x.y.z
+		if ( $version && ! preg_match( '!^\d+(\.\d+){1,2}$!', $version ) ) {
+			$this->warnings['requires_php_header_ignored'] = true;
+			// Ignore the readme value.
+			$version = '';
+		}
+
+		return $version;
+	}
+
+	/**
+	 * Sanitizes the Tested header to ensure that it's a valid version header
+	 *
+	 * @param string $version WordPress version that the theme is tested with.
+	 * @return string The sanitized $version
+	 */
+	protected function sanitize_tested_version( $version ) {
+		$version = trim( $version );
+
+		/**
+		 * Latest WordPress version
+		 *
+		 * @var string $latest_wordpress_version
+		 */
+		if ( defined( 'WP_CORE_LATEST_RELEASE' ) ) {
+			// When running on WordPress.org, this constant defines the latest WordPress release.
+			$latest_wordpress_version = WP_CORE_LATEST_RELEASE;
+		} else {
+			// Assume that the local environment being tested in is up to date.
+			$latest_wordpress_version = $GLOBALS['wp_version'];
+		}
+
+		if ( $version ) {
+			// Handle the edge-case of 'WordPress 5.0' and 'WP 5.0' for historical purposes.
+			$strip_phrases = array( 'WordPress', 'WP' );
+			$version       = trim( str_ireplace( $strip_phrases, '', $version ) );
+
+			// Strip off any -alpha, -RC, -beta suffixes, as these complicate comparisons and are rarely used.
+			list( $version, ) = explode( '-', $version );
+
+			if (
+				// x.y or x.y.z
+				! preg_match( '!^\d+\.\d(\.\d+)?$!', $version ) ||
+				// Allow themes to mark themselves as compatible with Stable+0.1 (trunk/master) but not higher
+				(
+					$latest_wordpress_version &&
+					version_compare( (float) $version, (float) $latest_wordpress_version + 0.1, '>' )
+				)
+			) {
+				$this->warnings['tested_header_ignored'] = true;
+				// Ignore the readme value.
+				$version = '';
+			}
+		}
+
+		return $version;
+	}
+
+	/**
+	 * Sanitizes the Requires at least header to ensure that it's a valid version header
+	 *
+	 * @param string $version The minim required WordPress version.
+	 * @return string The sanitized $version
+	 */
+	protected function sanitize_requires_version( $version ) {
+		$version                  = trim( $version );
+		$latest_wordpress_version = '5.9';
+
+		if ( $version ) {
+			// Handle the edge-case of 'WordPress 5.0' and 'WP 5.0' for historical purposes.
+			$strip_phrases = array( 'WordPress', 'WP', 'or higher', 'and above', '+' );
+			$version       = trim( str_ireplace( $strip_phrases, '', $version ) );
+
+			// Strip off any -alpha, -RC, -beta suffixes, as these complicate comparisons and are rarely used.
+			list( $version, ) = explode( '-', $version );
+
+			if (
+				// x.y or x.y.z
+				! preg_match( '!^\d+\.\d(\.\d+)?$!', $version ) ||
+				// Allow themes to mark themselves as requireing Stable+0.1 (trunk/master) but not higher
+				$latest_wordpress_version && ( (float) $version > (float) $latest_wordpress_version + 0.1 )
+			) {
+				$this->warnings['requires_header_ignored'] = true;
+				// Ignore the readme value.
+				$version = '';
+			}
+		}
+
+		return $version;
+	}
+
+}