"The function of rock and roll," LIFE magazine suggested in a March 1968 article, "may be not to revolutionize but to enliven and refresh the American musical comedy. . . . It is certainly the only music that today can lure young people back to the musical theater they long ago deserted." One can argue, of course, that it was musical theater that deserted young people in the 1950s and 1960s, and not the other way around -- but the article itself (wonderfully titled, "Whang! The Rock Musicals") had its square, unhip, well-meaning heart in the right place.
One of the works in question was the grooviest and, all these years later, still the most representative of all the late 1960s rock musicals: Hair. Here, on the anniversary of the play's April 29, 1968, Broadway opening, LIFE.com pays tribute to the self-proclaimed "American Tribal Love-Rock Musical" with photos made in rehearsals prior to that legendary opening night. (The notices from New York's notoriously prickly theater reviewers were almost universally raves.)
A Broadway revival of the show opened in March 2009 and won both a Tony and a Drama Desk Award for the best revival of a musical -- justifying Richard Zoglin's assertion in his TIME magazine review that 40 years after its debut, Hair felt "more daring than ever."
Let the sunshine in, y'all.