diff --git a/README.rst b/README.rst
index 60b9a9d..cdd81ca 100644
--- a/README.rst
+++ b/README.rst
@@ -433,22 +433,35 @@ Aliases
 ~~~~~~~
 
 The configargparse.ArgumentParser API inherits its class and method
-names from argparse and also provides the following shorter names for
+names from argparse and also provides the following shorter alias names for
 convenience:
 
--  p = configargparse.get_arg_parser()  # get global singleton instance
--  p = configargparse.get_parser()
--  p = configargparse.ArgParser()  # create a new instance
--  p = configargparse.Parser()
--  p.add_arg(..)
--  p.add(..)
--  options = p.parse(..)
+**Class Aliases:**
 
-HelpFormatters:
+- ``ArgParser`` = ``ArgumentParser`` (create a new instance)
+- ``Parser`` = ``ArgumentParser``
 
-- RawFormatter = RawDescriptionHelpFormatter
-- DefaultsFormatter = ArgumentDefaultsHelpFormatter
-- DefaultsRawFormatter = ArgumentDefaultsRawHelpFormatter
+**Method Aliases:**
+
+- ``p.add(..)`` = ``p.add_argument(..)``
+- ``p.add_arg(..)`` = ``p.add_argument(..)``
+- ``p.parse(..)`` = ``p.parse_args(..)``
+- ``p.parse_known(..)`` = ``p.parse_known_args(..)``
+
+**Function Aliases (for global singleton):**
+
+- ``configargparse.get_arg_parser()`` = ``configargparse.get_argument_parser()``
+- ``configargparse.get_parser()`` = ``configargparse.get_argument_parser()``
+- ``configargparse.getArgumentParser()`` = ``configargparse.get_argument_parser()``
+- ``configargparse.getArgParser()`` = ``configargparse.get_argument_parser()``
+- ``configargparse.getParser()`` = ``configargparse.get_argument_parser()``
+- ``configargparse.initArgumentParser()`` = ``configargparse.init_argument_parser()``
+
+**HelpFormatter Aliases:**
+
+- ``RawFormatter`` = ``RawDescriptionHelpFormatter``
+- ``DefaultsFormatter`` = ``ArgumentDefaultsHelpFormatter``
+- ``DefaultsRawFormatter`` = ``ArgumentDefaultsRawHelpFormatter``
 
 API Documentation
 ~~~~~~~~~~~~~~~~~
diff --git a/configargparse.py b/configargparse.py
index db92aa6..7219e49 100644
--- a/configargparse.py
+++ b/configargparse.py
@@ -968,10 +968,18 @@ def parse_known_args(
                         value = [elem.strip() for elem in value[1:-1].split(",")]
             env_var_args += self.convert_item_to_command_line_arg(action, key, value)
 
-        if nargs:
-            args = args + env_var_args
+        # Insert env var args before the first optional arg (starts with -)
+        # to preserve -- separator and positional args that come after it.
+        # If nargs is True, we still need to respect the -- separator.
+        insertion_index = 0
+        for i, arg in enumerate(args):
+            if arg.startswith(tuple(self.prefix_chars)):
+                insertion_index = i
+                break
         else:
-            args = env_var_args + args
+            # No optional args found, append to end
+            insertion_index = len(args)
+        args = args[:insertion_index] + env_var_args + args[insertion_index:]
 
         if env_var_args:
             self._source_to_settings[_ENV_VAR_SOURCE_KEY] = OrderedDict(
@@ -1054,10 +1062,18 @@ def parse_known_args(
                     ):
                         nargs = True
 
-            if nargs:
-                args = args + config_args
+            # Insert config args before the first optional arg (starts with -)
+            # to preserve -- separator and positional args that come after it.
+            # If nargs is True, we still need to respect the -- separator.
+            insertion_index = 0
+            for i, arg in enumerate(args):
+                if arg.startswith(tuple(self.prefix_chars)):
+                    insertion_index = i
+                    break
             else:
-                args = config_args + args
+                # No optional args found, append to end
+                insertion_index = len(args)
+            args = args[:insertion_index] + config_args + args[insertion_index:]
 
         # save default settings for use by print_values()
         default_settings = OrderedDict()
diff --git a/tests/test_configargparse.py b/tests/test_configargparse.py
index d46fde6..f7479af 100644
--- a/tests/test_configargparse.py
+++ b/tests/test_configargparse.py
@@ -1344,6 +1344,56 @@ def error_func(path):
             args="-g file.txt",
         )
 
+    def testDoubleDashSeparator(self):
+        """Test that -- separator correctly separates optional from positional args
+        when config file or env vars are used. Regression test for issue #298."""
+        # Create a config file with list option
+        config_file = tempfile.NamedTemporaryFile(
+            mode="w", delete=False, suffix=".conf"
+        )
+        config_file.write("list = [1, 2, 3]\n")
+        config_file.flush()
+        config_file.close()  # Close file to avoid Windows file locking issues
+
+        try:
+            # Test with config file
+            self.initParser(args_for_setting_config_path=["-c", "--config"])
+            self.parser.add_argument("--list", action="append")
+            self.parser.add_argument("positional_arg", nargs="*")
+
+            # Parse with -- separator
+            ns = self.parse(args=f"-c {config_file.name} -- foo bar")
+
+            # Positional args should only contain 'foo' and 'bar'
+            # NOT the config file values '1', '2', '3'
+            self.assertEqual(ns.positional_arg, ["foo", "bar"])
+            self.assertEqual(ns.list, ["1", "2", "3"])
+
+            # Test without -- separator (config file args should be inserted correctly)
+            ns = self.parse(args=f"-c {config_file.name} foo bar")
+            self.assertEqual(ns.positional_arg, ["foo", "bar"])
+            self.assertEqual(ns.list, ["1", "2", "3"])
+
+            # Test with env var and -- separator
+            self.initParser()
+            self.parser.add_argument("--list", action="append", env_var="MY_LIST")
+            self.parser.add_argument("positional_arg", nargs="*")
+
+            old_env = os.environ.get("MY_LIST")
+            try:
+                os.environ["MY_LIST"] = "[1,2,3]"
+                ns = self.parse(args="-- foo bar")
+                self.assertEqual(ns.positional_arg, ["foo", "bar"])
+                self.assertEqual(ns.list, ["1", "2", "3"])
+            finally:
+                if old_env is not None:
+                    os.environ["MY_LIST"] = old_env
+                elif "MY_LIST" in os.environ:
+                    del os.environ["MY_LIST"]
+
+        finally:
+            os.unlink(config_file.name)
+
 
 class TestConfigFileParsers(TestCase):
     """Test ConfigFileParser subclasses in isolation"""