FreeDrama.net, run by playwright D.M. Larson, offers royalty-free plays for schools and community theatres. Includes sections for children's, full-length, short, one-act, and small cast plays. It is requested that theatre groups request formal permission to perform, and send a copy of their program to the playwright.
This website offers links to "E-Scripts" from a variety of time periods and genres. Click "E-Scripts" on the top navigation menu to view a list of options. The list also includes an Electronic Text Archives page which provides resources for further playscript searches. Check carefully for production rights; many links lead to outside websites with their own performance policies.
ProPlay makes plays which have received professional productions available free-of-charge on the Web, to encourage their further production. In many cases, you'll find the complete text of the play here, along with production history, a biography of the playwright and contact information. In other instances, the playwright has chosen to post a portion of the play, and you may contact them or their representative for a complete copy.
This two-volume work provides amateur acting groups with summaries and other basic information on Catholic plays, including sources for obtaining full scripts and production rights. Address and pricing information may be out-of-date. More info