diff --git a/README.md b/README.md
index 3ac5d66..f21a469 100644
--- a/README.md
+++ b/README.md
@@ -72,6 +72,10 @@ cp -r templates/project-bootstrap/* ../my-project/ && cd ../my-project
 
 # Option B: Use the CLI (builds v2 scaffolding automatically)
 cd my-project && ../rebar/bin/rebar init
+
+# Option C: One-line installer (clones rebar to ~/.rebar, wires PATH)
+curl -fsSL https://raw.githubusercontent.com/willackerly/rebar/v3.0.0-alpha/setup-rebar.sh | bash
+# then: rebar new my-project -d "what it does"
 ```
 
 **What you get:** Contracts linked to code + agent coordination + immediate productivity boost
diff --git a/setup-rebar.sh b/setup-rebar.sh
new file mode 100755
index 0000000..81bebd2
--- /dev/null
+++ b/setup-rebar.sh
@@ -0,0 +1,121 @@
+#!/usr/bin/env bash
+# setup-rebar.sh — One-line installer for rebar.
+#
+# Clones rebar to $REBAR_DIR (default ~/.rebar), runs the canonical
+# `bin/install` to add ASK + rebar to your PATH, and exits pointing
+# you at `rebar new` / `rebar adopt` for actual project bootstrap.
+#
+# This is intentionally a thin shim over rebar's existing tooling
+# (`bin/install`, `rebar new`, `rebar adopt`) — not a parallel
+# bootstrap. Anything beyond clone + PATH wiring belongs in the
+# Go CLI so it stays in sync with the rest of the project.
+#
+# Usage (curl pipe):
+#   curl -fsSL https://raw.githubusercontent.com/willackerly/rebar/v3.0.0-alpha/setup-rebar.sh | bash
+#
+# Usage (local):
+#   ./setup-rebar.sh [--server HOST:PORT] [--dir PATH]
+
+set -euo pipefail
+
+REBAR_REPO="${REBAR_REPO:-https://github.com/willackerly/rebar.git}"
+REBAR_REF="${REBAR_REF:-v3.0.0-alpha}"
+REBAR_DIR="${REBAR_DIR:-$HOME/.rebar}"
+ASK_SERVER="${ASK_SERVER:-}"
+
+if [[ -t 1 ]]; then
+  RED=$'\033[0;31m'; GREEN=$'\033[0;32m'; YELLOW=$'\033[1;33m'
+  BLUE=$'\033[0;34m'; NC=$'\033[0m'
+else
+  RED=''; GREEN=''; YELLOW=''; BLUE=''; NC=''
+fi
+
+log()  { printf '%s[rebar]%s %s\n' "$BLUE"   "$NC" "$*"; }
+warn() { printf '%s[rebar]%s %s\n' "$YELLOW" "$NC" "$*" >&2; }
+err()  { printf '%s[rebar]%s %s\n' "$RED"    "$NC" "$*" >&2; }
+ok()   { printf '%s[rebar]%s %s\n' "$GREEN"  "$NC" "$*"; }
+
+usage() {
+  cat <<EOF
+rebar installer
+
+Clones rebar to \$REBAR_DIR (default ~/.rebar), then runs bin/install
+to add the ASK and rebar CLIs to your PATH. Project bootstrap (creating
+or adopting a project) is left to the rebar CLI itself — run
+\`rebar new\` or \`rebar adopt\` after this completes.
+
+Usage:
+  $0 [--server HOST:PORT] [--dir PATH] [--ref REF]
+  $0 --help
+
+Env vars (override flags):
+  REBAR_DIR    target install dir            (default: ~/.rebar)
+  REBAR_REPO   git remote to clone from      (default: github.com/willackerly/rebar)
+  REBAR_REF    branch/tag to check out       (default: v3.0.0-alpha)
+  ASK_SERVER   remote ASK server, written to your shell RC by bin/install
+
+Next steps after install:
+  rebar new my-project -d "what it does"   # create a new rebar project
+  rebar adopt                              # adopt rebar in an existing repo
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --server)   ASK_SERVER="$2"; shift 2 ;;
+    --server=*) ASK_SERVER="${1#--server=}"; shift ;;
+    --dir)      REBAR_DIR="$2"; shift 2 ;;
+    --dir=*)    REBAR_DIR="${1#--dir=}"; shift ;;
+    --ref)      REBAR_REF="$2"; shift 2 ;;
+    --ref=*)    REBAR_REF="${1#--ref=}"; shift ;;
+    -h|--help)  usage; exit 0 ;;
+    *)          err "unknown option: $1"; usage >&2; exit 2 ;;
+  esac
+done
+
+if ! command -v git >/dev/null 2>&1; then
+  err "git is required. Install it and re-run."
+  exit 1
+fi
+
+if [[ -d "$REBAR_DIR/.git" ]]; then
+  log "Updating existing rebar checkout at $REBAR_DIR"
+  if ! git -C "$REBAR_DIR" diff --quiet || ! git -C "$REBAR_DIR" diff --cached --quiet; then
+    warn "$REBAR_DIR has uncommitted changes — skipping fetch/checkout"
+  else
+    git -C "$REBAR_DIR" fetch --tags origin "$REBAR_REF"
+    git -C "$REBAR_DIR" checkout "$REBAR_REF"
+    git -C "$REBAR_DIR" pull --ff-only origin "$REBAR_REF" || true
+  fi
+elif [[ -e "$REBAR_DIR" ]]; then
+  err "$REBAR_DIR exists but is not a git checkout."
+  err "Move it aside or set REBAR_DIR=<other path> and re-run."
+  exit 1
+else
+  log "Cloning $REBAR_REPO ($REBAR_REF) → $REBAR_DIR"
+  git clone --branch "$REBAR_REF" --depth=1 "$REBAR_REPO" "$REBAR_DIR"
+fi
+
+if [[ ! -x "$REBAR_DIR/bin/install" ]]; then
+  err "$REBAR_DIR/bin/install not found or not executable."
+  err "The clone may have failed or the ref does not contain bin/install."
+  exit 1
+fi
+
+install_args=()
+[[ -n "$ASK_SERVER" ]] && install_args+=(--server "$ASK_SERVER")
+log "Running $REBAR_DIR/bin/install ${install_args[*]:-}"
+"$REBAR_DIR/bin/install" "${install_args[@]}"
+
+ok "rebar installed at $REBAR_DIR (ref: $REBAR_REF)"
+cat <<EOF
+
+${BLUE}Next steps:${NC}
+  • Open a new terminal (or source your shell RC) so PATH picks up rebar
+  • ${GREEN}rebar new my-project -d "what it does"${NC}   # new project
+  • ${GREEN}rebar adopt${NC}                              # adopt rebar in an existing repo
+
+${BLUE}Docs:${NC}
+  • https://github.com/willackerly/rebar/blob/$REBAR_REF/QUICKSTART.md
+  • https://github.com/willackerly/rebar/blob/$REBAR_REF/SETUP.md
+EOF