Now in its tenth year, this three-day event offers free readings and open rehearsals of plays and musicals being developed by more than 40 area theater companies, including Adventure Theatre, Catholic University, The Hub Theatre, No Rules Theatre Company, Scena Theatre, Signature Theatre and Theater J. There's also a New Playwrights' Slam with short selections from new works by budding locals. Saturday, Sept. 3, through Monday, Sept. 5. Kennedy Center. Free. Call 202-467-4600 or visit kennedy-center.org for more details and specific performance times.