diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 944da02..a34064b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,14 +14,25 @@ concurrency:
 
 jobs:
   specs:
-    name: Specs (Ruby ${{ matrix.ruby }})
+    name: Specs (Ruby ${{ matrix.ruby }}, Rails ${{ matrix.rails }})
     runs-on: ubuntu-latest
     timeout-minutes: 10
 
     strategy:
       fail-fast: false
       matrix:
-        ruby: ['3.0', '3.1', '3.2', '3.3']
+        ruby: ['3.0', '3.1', '3.2', '3.3', '3.4']
+        rails: ['6.1', '7.0', '7.1', '7.2', '8.0', '8.1']
+        exclude:
+          # Rails < 7.1 requires mutex_m, dropped from the default gems in 3.4.
+          - {ruby: '3.4', rails: '6.1'}
+          - {ruby: '3.4', rails: '7.0'}
+          # Each Rails version's own minimum Ruby.
+          - {ruby: '3.0', rails: '7.2'}
+          - {ruby: '3.0', rails: '8.0'}
+          - {ruby: '3.1', rails: '8.0'}
+          - {ruby: '3.0', rails: '8.1'}
+          - {ruby: '3.1', rails: '8.1'}
 
     services:
       postgres:
@@ -38,6 +49,9 @@ jobs:
           --health-timeout 5s
           --health-retries 5
 
+    env:
+      BUNDLE_GEMFILE: gemfiles/rails_${{ matrix.rails }}.gemfile
+
     steps:
       - uses: actions/checkout@v4
 
diff --git a/.gitignore b/.gitignore
index c8a9280..71d070c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,8 @@
 /.bundle/
 /.yardoc
 /Gemfile.lock
+# A lockfile records one Ruby's resolution, and the CI matrix spans several.
+/gemfiles/*.gemfile.lock
 /_yardoc/
 /coverage/
 /doc/
@@ -9,6 +11,7 @@
 /tmp/
 
 /spec/dummy/log/*
+/spec/dummy/tmp/
 
 # Ignore vim swap files
 *.swp
diff --git a/Appraisals b/Appraisals
new file mode 100644
index 0000000..d1dfbeb
--- /dev/null
+++ b/Appraisals
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# One appraisal per supported Rails version. `bundle exec appraisal install`
+# regenerates gemfiles/ and their lockfiles.
+
+# concurrent-ruby >= 1.3.5 dropped the implicit `require 'logger'` that
+# Rails < 7.1 relies on.
+CONCURRENT_RUBY_PIN = '< 1.3.5'
+
+appraise 'rails-6.1' do
+  gem 'activerecord', '~> 6.1.0'
+  gem 'activesupport', '~> 6.1.0'
+  gem 'concurrent-ruby', CONCURRENT_RUBY_PIN
+end
+
+appraise 'rails-7.0' do
+  gem 'activerecord', '~> 7.0.0'
+  gem 'activesupport', '~> 7.0.0'
+  gem 'concurrent-ruby', CONCURRENT_RUBY_PIN
+end
+
+appraise 'rails-7.1' do
+  gem 'activerecord', '~> 7.1.0'
+  gem 'activesupport', '~> 7.1.0'
+end
+
+appraise 'rails-7.2' do
+  gem 'activerecord', '~> 7.2.0'
+  gem 'activesupport', '~> 7.2.0'
+end
+
+appraise 'rails-8.0' do
+  gem 'activerecord', '~> 8.0.0'
+  gem 'activesupport', '~> 8.0.0'
+end
+
+appraise 'rails-8.1' do
+  gem 'activerecord', '~> 8.1.0'
+  gem 'activesupport', '~> 8.1.0'
+end
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ef4bb88..e2158b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Support for Rails 7.0, 7.1, 7.2, 8.0, and 8.1. Rails 6.1 remains supported.
+- Support for Ruby 3.3 and 3.4. Ruby 3.0 remains the minimum.
 - Declared and tested the supported Ruby versions (#10).
 - The specs and RuboCop now run in GitHub Actions (#9).
 - Gem metadata: `source_code_uri`, `changelog_uri`, `bug_tracker_uri`, and
@@ -16,10 +18,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- `activerecord` and `activesupport` requirements widen from `~> 6.1` to
+  `>= 6.1, < 9`, and the `< 3.4` Ruby ceiling is removed. Rails 6.1 and 7.0
+  cannot run on Ruby 3.4; every other combination is exercised in CI.
 - The released gem now ships only `lib/`, the README, the LICENSE, and this
   changelog. Previous releases also carried repository scaffolding — CI
   configuration, `Rakefile`, `bin/`, and dotfiles — that a host app never loads.
 
+### Removed
+
+- `pg` is no longer a runtime dependency. Revisions still require PostgreSQL
+  column types, but the adapter is the host application's to declare, so the
+  gem no longer forces `pg` into its bundle.
+
 ### Fixed
 
 - Made the spec suite runnable and trustworthy again (#8).
diff --git a/Gemfile b/Gemfile
index 6a4ac30..cd29f96 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,10 +5,6 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in recorder.gemspec
 gemspec
 
-# Development pins, removable with the Rails upgrade.
-
-# concurrent-ruby >= 1.3.5 has no implicit `require 'logger'`; Rails < 7.1 needs it.
-gem 'concurrent-ruby', '< 1.3.5'
-
-# rubocop-factory_bot >= 2.24 needs a newer rubocop than standard 1.29 allows.
+# rubocop-factory_bot >= 2.24 needs a newer rubocop than jetrockets-standard 1.29
+# allows, and its config fails to load against the older one.
 gem 'rubocop-factory_bot', '~> 2.23.0'
diff --git a/README.md b/README.md
index 1d1c04b..207efbb 100644
--- a/README.md
+++ b/README.md
@@ -4,9 +4,20 @@ Recorder tracks changes of your Rails models
 
 ## Requirements
 
-- Ruby >= 3.0, < 3.4
-- Rails 6.1
 - PostgreSQL — revisions are stored in `jsonb` and `inet` columns
+- Ruby and Rails per the table below
+
+| Rails | Supported Ruby |
+|-------|----------------|
+| 6.1   | 3.0 – 3.3      |
+| 7.0   | 3.0 – 3.3      |
+| 7.1   | 3.0 – 3.4      |
+| 7.2   | 3.1 – 3.4      |
+| 8.0   | 3.2 – 3.4      |
+| 8.1   | 3.2 – 3.4      |
+
+Rails 6.1 and 7.0 cannot run on Ruby 3.4 — they require `mutex_m`, which left the
+default gems in that release. Every combination in the table is exercised in CI.
 
 ## Installation
 
@@ -84,6 +95,19 @@ The gem is under active maintenance and these defects are known as of 1.2.3:
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
+The specs need a PostgreSQL server. Connection settings are read from the
+environment — `RECORDER_DB_HOST`, `RECORDER_DB_PORT`, `RECORDER_DB_USERNAME`,
+`RECORDER_DB_PASSWORD`, `RECORDER_DB_NAME` — and default to `postgres:postgres`
+on `localhost:5432` against a `recorder_test` database, which must already exist.
+
+`rake spec` runs against whichever Rails version the root `Gemfile` resolves to.
+To run against a specific one, use the appraisal gemfiles:
+
+```bash
+bundle exec appraisal install            # once, to generate gemfiles/
+bundle exec appraisal rails-7.2 rake spec
+```
+
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
 
 ## Contributing
diff --git a/gemfiles/rails_6.1.gemfile b/gemfiles/rails_6.1.gemfile
new file mode 100644
index 0000000..1ce972d
--- /dev/null
+++ b/gemfiles/rails_6.1.gemfile
@@ -0,0 +1,10 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 6.1.0"
+gem "activesupport", "~> 6.1.0"
+gem "concurrent-ruby", "< 1.3.5"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_7.0.gemfile b/gemfiles/rails_7.0.gemfile
new file mode 100644
index 0000000..eba5190
--- /dev/null
+++ b/gemfiles/rails_7.0.gemfile
@@ -0,0 +1,10 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 7.0.0"
+gem "activesupport", "~> 7.0.0"
+gem "concurrent-ruby", "< 1.3.5"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_7.1.gemfile b/gemfiles/rails_7.1.gemfile
new file mode 100644
index 0000000..a3d29be
--- /dev/null
+++ b/gemfiles/rails_7.1.gemfile
@@ -0,0 +1,9 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 7.1.0"
+gem "activesupport", "~> 7.1.0"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_7.2.gemfile b/gemfiles/rails_7.2.gemfile
new file mode 100644
index 0000000..4028302
--- /dev/null
+++ b/gemfiles/rails_7.2.gemfile
@@ -0,0 +1,9 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 7.2.0"
+gem "activesupport", "~> 7.2.0"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_8.0.gemfile b/gemfiles/rails_8.0.gemfile
new file mode 100644
index 0000000..8cdabe7
--- /dev/null
+++ b/gemfiles/rails_8.0.gemfile
@@ -0,0 +1,9 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 8.0.0"
+gem "activesupport", "~> 8.0.0"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_8.1.gemfile b/gemfiles/rails_8.1.gemfile
new file mode 100644
index 0000000..3715196
--- /dev/null
+++ b/gemfiles/rails_8.1.gemfile
@@ -0,0 +1,9 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rubocop-factory_bot", "~> 2.23.0"
+gem "activerecord", "~> 8.1.0"
+gem "activesupport", "~> 8.1.0"
+
+gemspec path: "../"
diff --git a/recorder.gemspec b/recorder.gemspec
index 5532486..7178a54 100644
--- a/recorder.gemspec
+++ b/recorder.gemspec
@@ -27,16 +27,19 @@ Gem::Specification.new do |spec|
   spec.files = Dir['lib/**/*', 'CHANGELOG.md', 'LICENSE.txt', 'README.md'].select { |f| File.file?(f) }
   spec.require_paths = ['lib']
 
-  spec.required_ruby_version = ['>= 3.0', '< 3.4']
+  spec.required_ruby_version = '>= 3.0'
 
-  spec.add_dependency 'activerecord', '~> 6.1'
-  spec.add_dependency 'activesupport', '~> 6.1'
-  spec.add_dependency 'pg'
-  spec.add_dependency 'request_store'
+  spec.add_dependency 'activerecord', '>= 6.1', '< 9'
+  spec.add_dependency 'activesupport', '>= 6.1', '< 9'
+  spec.add_dependency 'request_store', '>= 1.0'
 
+  spec.add_development_dependency 'appraisal', '~> 2.5'
   spec.add_development_dependency 'bundler', '>= 2.0'
-  spec.add_development_dependency 'generator_spec'
+  spec.add_development_dependency 'generator_spec', '~> 0.9'
   spec.add_development_dependency 'jetrockets-standard'
+  # Revisions are stored in `jsonb` and `inet` columns; the dummy app is PostgreSQL.
+  # Host apps supply their own adapter.
+  spec.add_development_dependency 'pg', '>= 1.0'
   spec.add_development_dependency 'rake', '~> 13.0'
-  spec.add_development_dependency 'rspec-rails'
+  spec.add_development_dependency 'rspec-rails', '>= 5.0'
 end
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index be10794..6957fce 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -4,7 +4,15 @@
 require File.expand_path('../spec/dummy/config/environment', __dir__)
 require 'rspec/rails'
 
-ActiveRecord::MigrationContext.new(File.expand_path('dummy/db/migrate', __dir__), ActiveRecord::SchemaMigration).migrate
+migrations_path = File.expand_path('dummy/db/migrate', __dir__)
+
+# Rails 6.1 requires the schema migration class here. It became optional in 7.0
+# and was removed in 7.2.
+if ActiveRecord.version < Gem::Version.new('7.0')
+  ActiveRecord::MigrationContext.new(migrations_path, ActiveRecord::SchemaMigration).migrate
+else
+  ActiveRecord::MigrationContext.new(migrations_path).migrate
+end
 
 ActiveRecord::Migration.check_pending! if ActiveRecord::Migration.respond_to?(:check_pending!)