The Dramatist's Bill of Rights
Dramatists Guild of America
The Dramatists Guild's statement of the industry standards playwrights should expect when a script is produced. It covers copyright ownership, script approval and artistic integrity, royalties, billing, subsidiary rights thresholds, and attending rehearsals, with downloadable English and Spanish PDFs. It is free and substantive, and no free alternative comes close for what a playwright should and shouldn't sign.
More resources on Playwriting
New Play Exchange
A searchable database of scripts by living playwrights, run by the National New Play Network. Members browse thousands of new plays, read recommendations from other writers and literary managers, and post their own work for theatres to find.
How Plays Work
An analysis of dramatic technique by the playwright who founded Britain's first postgraduate playwriting programme. Edgar looks at action, character, genre, structure, scenes, and devices across a wide range of plays, from Greek tragedy to contemporary drama. It looks at how working plays get their effects across genres and periods, not at rules.
The Playwright's Guidebook: An Insightful Primer on the Art of Dramatic Writing
A playwriting primer built around action, conflict, and the dramatic event. It covers how to handle story, character, dialogue, and theme. Exercises in each chapter take the reader from first ideas through full drafts and rewrites. This is the best practical book for a first play. Egri gives the theory, and this book gives an exercise-driven workflow.
Backwards and Forwards: A Technical Manual for Reading Plays
A short manual on reading scripts as blueprints for performance. Ball traces how each event causes the next, and uses Hamlet to show how to track action, obstacles, exposition, and character through a play. Other books tell you to read plays, but this one teaches the causal action-by-action reading that playwrights need.