diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9e3ea4f525..dccaa35a71 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -26,14 +26,15 @@ During this transition:
 
 Git hooks are installed automatically when you run the standard setup commands. They will run automatic linting on **all changed files (staged + unstaged + untracked)** - making commits fast while preventing CI failures.
 
+- After cloning the repo, run `bin/setup` from the root directory to install all dependencies.
+
 - After updating code via Git, to prepare all examples:
 
 ```sh
-cd react_on_rails/
 bundle && pnpm install && rake shakapacker_examples:gen_all && rake node_package && rake
 ```
 
-See [Dev Initial Setup](#dev-initial-setup) below for, well... initial setup,
+See [Dev Initial Setup](#dev-initial-setup) below for initial setup details,
 and [Running tests](#running-tests) for more details on running tests.
 
 # IDE/IDE SETUP
@@ -199,9 +200,57 @@ or the equivalent command for your package manager.
 
 ## Dev Initial Setup
 
-### Prereqs
+### Quick Setup (Recommended)
+
+After checking out the repo and ensuring you have Ruby and Node version managers set up (such as rvm and nvm, or rbenv and nodenv, etc.) with the correct versions active, run:
+
+```sh
+# First, verify your versions match the project requirements
+ruby -v  # Should show 3.4.x or version in .ruby-version
+node -v  # Should show 22.x or version in .node-version
+
+# Then run the setup script
+bin/setup
+
+# Or skip Pro setup (for contributors without Pro access)
+bin/setup --skip-pro
+```
+
+This single command installs all dependencies across the monorepo:
+
+- Root pnpm and bundle dependencies
+- Builds the node package
+- Sets up `react_on_rails/spec/dummy`
+- Sets up `react_on_rails_pro` (if present)
+- Sets up `react_on_rails_pro/spec/dummy` (if present)
+- Sets up `react_on_rails_pro/spec/execjs-compatible-dummy` (if present)
+
+### Manual Setup (Alternative)
+
+If you prefer to set up manually or need more control:
+
+1. Install root dependencies:
+
+```sh
+bundle install
+pnpm install
+```
+
+2. Build the node package:
+
+```sh
+rake node_package
+```
+
+3. Set up the dummy app:
+
+```sh
+cd react_on_rails/spec/dummy
+bundle install
+pnpm install
+```
 
-After checking out the repo, making sure you have Ruby and Node version managers set up (such as rvm and nvm, or rbenv and nodenv, etc.), cd to `react_on_rails/spec/dummy` and run `bin/setup` to install ruby dependencies. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 ### Local Node Package
 
diff --git a/bin/setup b/bin/setup
new file mode 100755
index 0000000000..3c711f7411
--- /dev/null
+++ b/bin/setup
@@ -0,0 +1,284 @@
+#!/usr/bin/env bash
+#
+# bin/setup - Unified development environment setup for React on Rails
+#
+# This script installs all dependencies across all directories in the monorepo,
+# making it easy for new contributors to get started quickly.
+#
+# Usage:
+#   bin/setup              # Full setup of all packages
+#   bin/setup --skip-pro   # Skip Pro package setup
+#   bin/setup --help       # Show this help message
+#
+
+set -euo pipefail
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Script directory (for running from anywhere)
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
+
+# Track start time for elapsed time display
+START_TIME=$(date +%s)
+
+# Flags
+SKIP_PRO=false
+
+show_help() {
+  echo "Usage: bin/setup [OPTIONS]"
+  echo ""
+  echo "Sets up the React on Rails development environment by installing"
+  echo "all dependencies across the monorepo."
+  echo ""
+  echo "Options:"
+  echo "  --skip-pro  Skip react_on_rails_pro setup (for contributors without Pro access)"
+  echo "  --help      Show this help message"
+  echo ""
+  echo "This script will:"
+  echo "  1. Install root pnpm and bundle dependencies"
+  echo "  2. Build the node package"
+  echo "  3. Set up react_on_rails/spec/dummy"
+  echo "  4. Set up react_on_rails_pro (if present and not skipped)"
+  echo "  5. Set up react_on_rails_pro/spec/dummy (if present and not skipped)"
+  echo "  6. Set up react_on_rails_pro/spec/execjs-compatible-dummy (if present and not skipped)"
+}
+
+print_step() {
+  echo -e "\n${BLUE}==>${NC} ${GREEN}$1${NC}"
+}
+
+print_warning() {
+  echo -e "${YELLOW}Warning:${NC} $1"
+}
+
+print_error() {
+  echo -e "${RED}Error:${NC} $1"
+}
+
+print_success() {
+  echo -e "${GREEN}✓${NC} $1"
+}
+
+check_prerequisites() {
+  local missing=()
+
+  if ! command -v pnpm &> /dev/null; then
+    missing+=("pnpm")
+  fi
+
+  if ! command -v bundle &> /dev/null; then
+    missing+=("bundler")
+  fi
+
+  if ! command -v node &> /dev/null; then
+    missing+=("node")
+  fi
+
+  if ! command -v ruby &> /dev/null; then
+    missing+=("ruby")
+  fi
+
+  if [ ${#missing[@]} -ne 0 ]; then
+    print_error "Missing required tools: ${missing[*]}"
+    echo ""
+    echo "Please install the following before running this script:"
+    for tool in "${missing[@]}"; do
+      case $tool in
+        pnpm)
+          echo "  - pnpm: https://pnpm.io/installation"
+          ;;
+        bundler)
+          echo "  - bundler: gem install bundler"
+          ;;
+        node)
+          echo "  - node: https://nodejs.org/ (or use nvm/nodenv)"
+          ;;
+        ruby)
+          echo "  - ruby: https://www.ruby-lang.org/ (or use rvm/rbenv)"
+          ;;
+      esac
+    done
+    exit 1
+  fi
+
+  # Display versions found
+  echo "  Ruby:    $(ruby -v | head -1)"
+  echo "  Node:    $(node -v)"
+  echo "  pnpm:    $(pnpm -v)"
+  echo "  Bundler: $(bundle -v)"
+}
+
+verify_root_directory() {
+  if [ ! -f "$ROOT_DIR/Rakefile" ]; then
+    print_error "Rakefile not found. Are you in the correct directory?"
+    print_error "Expected location: $ROOT_DIR/Rakefile"
+    exit 1
+  fi
+
+  if [ ! -f "$ROOT_DIR/package.json" ]; then
+    print_error "package.json not found. Are you in the correct directory?"
+    print_error "Expected location: $ROOT_DIR/package.json"
+    exit 1
+  fi
+}
+
+install_dependencies() {
+  local dir="$1"
+  local name="$2"
+
+  if [ ! -d "$dir" ]; then
+    print_warning "Directory not found: $dir (skipping)"
+    return 0
+  fi
+
+  print_step "Setting up $name..."
+  cd "$dir"
+
+  # Install Ruby dependencies if Gemfile exists
+  if [ -f "Gemfile" ]; then
+    echo "  Installing Ruby dependencies..."
+    if bundle check &> /dev/null; then
+      print_success "Ruby dependencies already satisfied"
+    else
+      if ! bundle install; then
+        print_error "Failed to install Ruby dependencies in $name"
+        exit 1
+      fi
+      print_success "Ruby dependencies installed"
+    fi
+  fi
+
+  # Install JS dependencies if package.json exists
+  # Use --frozen-lockfile to match CI behavior and ensure lockfile integrity
+  if [ -f "package.json" ]; then
+    echo "  Installing JavaScript dependencies..."
+    if ! pnpm install --frozen-lockfile; then
+      print_error "Failed to install JavaScript dependencies in $name"
+      exit 1
+    fi
+    print_success "JavaScript dependencies installed"
+  fi
+
+  cd "$ROOT_DIR"
+}
+
+build_node_package() {
+  # Builds TypeScript packages and runs pnpm yalc:publish for local development.
+  # This compiles node_package/src/ to lib/ and makes packages available locally.
+  print_step "Building node package..."
+  if ! rake node_package; then
+    print_error "Failed to build node package"
+    exit 1
+  fi
+  print_success "Node package built"
+}
+
+verify_build_artifacts() {
+  print_step "Verifying build artifacts..."
+
+  local artifact="packages/react-on-rails/lib/ReactOnRails.full.js"
+  if [ ! -f "$ROOT_DIR/$artifact" ]; then
+    print_error "Build failed: $artifact not found"
+    print_error "Expected location: $ROOT_DIR/$artifact"
+    exit 1
+  fi
+  print_success "Build artifacts verified"
+}
+
+show_elapsed_time() {
+  local END_TIME=$(date +%s)
+  local ELAPSED=$((END_TIME - START_TIME))
+  local MINUTES=$((ELAPSED / 60))
+  local SECONDS=$((ELAPSED % 60))
+
+  if [ $MINUTES -gt 0 ]; then
+    echo -e "Total time: ${BLUE}${MINUTES}m ${SECONDS}s${NC}"
+  else
+    echo -e "Total time: ${BLUE}${SECONDS}s${NC}"
+  fi
+}
+
+main() {
+  # Parse arguments
+  while [[ $# -gt 0 ]]; do
+    case $1 in
+      --help|-h)
+        show_help
+        exit 0
+        ;;
+      --skip-pro)
+        SKIP_PRO=true
+        shift
+        ;;
+      *)
+        print_error "Unknown option: $1"
+        echo "Run 'bin/setup --help' for usage information."
+        exit 1
+        ;;
+    esac
+  done
+
+  echo -e "${GREEN}Setting up React on Rails development environment...${NC}"
+  echo ""
+
+  cd "$ROOT_DIR"
+
+  # Verify we're in the correct directory
+  print_step "Verifying project directory..."
+  verify_root_directory
+  print_success "Project directory verified"
+
+  # Check prerequisites
+  print_step "Checking prerequisites..."
+  check_prerequisites
+  print_success "All prerequisites found"
+
+  # Root dependencies
+  install_dependencies "$ROOT_DIR" "root directory"
+
+  # Build node package
+  build_node_package
+
+  # Verify build artifacts
+  verify_build_artifacts
+
+  # react_on_rails/spec/dummy
+  install_dependencies "$ROOT_DIR/react_on_rails/spec/dummy" "react_on_rails/spec/dummy"
+
+  # react_on_rails_pro (if present and not skipped)
+  if [ "$SKIP_PRO" = true ]; then
+    print_warning "Skipping react_on_rails_pro setup (--skip-pro flag)"
+  elif [ -d "$ROOT_DIR/react_on_rails_pro" ]; then
+    install_dependencies "$ROOT_DIR/react_on_rails_pro" "react_on_rails_pro"
+
+    # react_on_rails_pro/spec/dummy
+    install_dependencies "$ROOT_DIR/react_on_rails_pro/spec/dummy" "react_on_rails_pro/spec/dummy"
+
+    # react_on_rails_pro/spec/execjs-compatible-dummy
+    install_dependencies "$ROOT_DIR/react_on_rails_pro/spec/execjs-compatible-dummy" "react_on_rails_pro/spec/execjs-compatible-dummy"
+  fi
+
+  echo ""
+  echo -e "${GREEN}========================================${NC}"
+  echo -e "${GREEN}Setup complete!${NC}"
+  echo -e "${GREEN}========================================${NC}"
+  show_elapsed_time
+  echo ""
+  echo "Git hooks have been automatically installed during setup."
+  echo "They will run linting on changed files before each commit."
+  echo ""
+  echo "You can now run:"
+  echo "  rake              # Run all tests"
+  echo "  rake lint         # Run linters"
+  echo "  rake all_but_examples  # Run tests (excluding generator examples)"
+  echo ""
+  echo "For more information, see CONTRIBUTING.md"
+}
+
+main "$@"