Sing-a-long, San Francisco, it's your last chance.

The sing-a-long Sound of Music, still thriving in London and now across the United States, ends its second successful engagement in the City by the Bay July 7 at the historic Castro Theatre. The popular interactive showings of the world famous Julie Andrews musical drama began again June 29.

A sell-out success at London's Prince Charles Cinema and in a tour throughout Britain, this special "Sound of Music" gives audiences the chance to do what they've always wanted to do during the sugary-sweet Julie Andrews flick: dress up as nuns, wave edelweiss and sing along to the Rogers and Hammerstein tunes to the rhythm of the bouncing ball. A complimentary interactive pack accompanies the movie (a plastic nun is among the goodies) with a mystery host leading a vocal warm up, introducing a comprehensive list of shouted comments and gestures (a la "Rocky Horror") and judging the costume contest.

That final part of the evening has resulted in the most creative aspects of the "Sing-a-Long Sound of Music." Any costume, aside from those nasty Nazis, is welcome, and they have ranged from the usual (the Von Trapp children in their curtains) to the bizarre (goats — with and without Lonely Goatherds — to a young man in a gold lycra catsuit (give up? He's Ray, a Drop of Golden Sun)).

The Castro, named for the street from which the world-famous San Francisco gay neighborhood takes its moniker, is a renovated art deco theatre from 1922 which normally runs a classic and art film repertory. The theatre's sign, as visible as the neighborhood's giant rainbow flag, is the Castro district's main landmark. Tickets are $22.50-$20. For reservations, call (510) 601-TWEB or at http://www.ticketweb.com. The Castro Theatre is located on Castro at Market Street.

— By Christine Ehren