Underscores (_s): The Classic WordPress Starter Theme — and What Replaced It
Automattic/_s (Underscores) earned iconic status — roughly ~11k stars — as the clean, underscored starter theme that gave you a "1000-hour head start" without imposing a framework aesthetic. For more than a decade, "_s" was the answer when someone asked "how do I start a custom WordPress theme?" It taught template hierarchy, minimal markup, and WordPress coding standards without the baggage of a commercial theme framework.
Important 2025–2026 status note
The GitHub description now flags the project as inactive, pointing ThemeShaper and block-theme learning resources as the future path. Automattic's energy has shifted toward block themes, full site editing (FSE), and the Site Editor as the primary customization surface. Treat _s as legacy-but-known, not the first recommendation for a greenfield theme in 2026 — but do not dismiss it if you inherit an _s-based codebase or want to learn classic theme fundamentals.
What made Underscores great
- Minimal, well-commented template hierarchy (
index.php,single.php,archive.php, etc.) - No CSS framework locking you into Bootstrap or Foundation
- Ideal teaching tool for how WordPress themes actually resolve templates
- Generator at underscores.me to rename prefixes in one step
- Neutral styling so your design system starts from zero, not from fighting inherited CSS
Underscores assumed you would add your own build pipeline — or none at all for simple projects. That was a feature when CSS was a single style.css and jQuery was acceptable everywhere. It is a limitation when every modern theme expects Vite, Tailwind, and componentized markup.
Who still benefits from _s today
- Developers learning WordPress theme development for the first time
- Teams maintaining existing _s child themes with years of client-specific code
- Projects on hosts where Composer and Node builds are impractical
- Educators teaching the template hierarchy before introducing block themes
When NOT to start with _s in 2026
- New agency client builds expecting modern tooling — use Sage instead
- Site Editor-first projects — use create-block-theme or a block starter
- Headless WordPress — theme PHP matters less; invest in WPGraphQL and front-end app structure
- Long-term greenfield with ACF modules — _s works, but you will rebuild tooling Sage already includes
What to use instead today
- Roots Sage for developer-owned custom themes with Vite, Tailwind, and Blade
- Block / FSE starters (e.g.
create-block-theme) for Site Editor workflows - Timber when your team standardized on Twig templates
- Bedrock for project structure regardless of theme choice
Classic _s workflow (if you are maintaining one)
- Identify whether you have a direct _s fork or a child theme of a renamed _s base.
- Map template files to URL patterns using the template hierarchy debug approach (Query Monitor or built-in body classes).
- Keep security updates on WordPress core, plugins, and PHP versions — _s itself will not receive feature updates.
- Document custom post types, ACF field groups, and widget areas for handoff.
- For repetitive ACF edits across many pages, add Quickfields Bulk Editor for ACF — see the Quickfields walkthrough.
Underscores vs Sage vs block themes
| Factor | _s | Sage | Block theme |
|---|---|---|---|
| Status | Inactive | Active | WordPress core direction |
| Toolchain | Bring your own | Vite + Tailwind + Blade | theme.json + blocks |
| Learning curve | Low for PHP basics | Medium (Composer/npm) | Medium (FSE concepts) |
| Handoff to non-devs | Classic editor / ACF | ACF + custom admin | Site Editor native |
Gotchas for legacy _s sites
- No upstream features — security depends on core and plugins, not theme updates from Automattic.
- jQuery-era JavaScript — audit enqueued scripts; modern accessibility and performance standards may require refactors.
- ACF without bulk tools — location-page libraries become painful; Quickfields or Quickfields Pro helps text-heavy field groups.
If you still maintain an _s child theme
Keep security updates on plugins and PHP; do not expect new _s features. For ACF-heavy sites on classic PHP themes, bulk field editing still helps — try Quickfields Bulk Editor for ACF. Debug slow templates with Query Monitor.
FAQ
Is _s dead? Inactive for new development, not deleted — repos and forks remain usable.
Should beginners still learn _s? Learning template hierarchy via _s is valuable; just know block themes are the parallel skill worth adding.
Can I migrate _s to Sage? Possible as a rewrite — budget time to port templates to Blade and rebuild assets.
Does _s work with WooCommerce? Yes — many WooCommerce child themes historically started from Underscores patterns; WooCommerce template overrides still follow classic PHP theme rules.
What about accessibility? _s was minimal markup — accessibility depends entirely on what you added. Modern audits (landmarks, focus states, keyboard nav) are your responsibility regardless of starter theme.
Historical context worth knowing
Underscores shaped a generation of WordPress theme developers who later adopted Composer, Twig, Blade, and block themes. If you read older tutorials referencing _s or ThemeShaper, translate their lessons to current tooling: the template hierarchy concepts transfer directly; the recommended starter does not.
For greenfield ACF marketing sites in 2026, the practical path is Sage + Bedrock + Quickfields for content ops — not a fresh _s fork unless constraints force classic PHP simplicity.
Learning _s remains worthwhile in computer science and web development curricula where the goal is understanding WordPress internals — just pair those lessons with exposure to block themes and modern scaffolds so students graduate with current hireable skills.