JOSEPH AND THE AMAZING TECHNICOLOR DREAMCOAT - At the Olney, through Oct. 1.

The Catholic Unversity production of "Joseph and the Amazing Technicolor Dreamcoat" is back for its third engagement this year - an opportunity for anyone who missed it to see it, for anyone who saw it to see it again, and for a critic who didn't say it was the best thing going this summer to say so.

Written by Tim Rice and Andrew Lloyd Webber, the authors of the current London hit "Evita" and of "Jesus Christ, Superstar," the mixed-style musical is at once excellent satire and respectful folk popularization of the Bible - witty and touching, sophisticated in its approach and simply and good in its enthusiasm.

But it's the student production - given last spring at Catholic University, and as the opening engagement at Olney Theatre, where it's now closing the season - that gives it its sheen. A comparison with the British record, which is not a cast recording but an especially made concert performance, will show you how much the Catholic University cast, directed by James D. Waring, has contributed.

Mark Heckler as the bouncy goody-goody you can't help loving as he offers to treat you with a back view of his beautiful coat, Ayl Mack as a shiningly earnest narrator, Wayne Dilts as a confused but snuggly Jacob, Blaise Corrigan as a gyrating Pharoah, Joseph's brothers who pitch into any musical style that comes along - the cast, as is, could compete with the best of professionals.

It is, in fact, that competition that makes "Joseph" seem even better, at summer's end, than at the beginning. We have had the professional musicals - the shopworn "Oh, Kay!," the more-noise-than-music "Wiz," the good-but-still-second-string company of "Annie." And meanwhile, as the professional casts at Olney have provided almost uniformly top theater this summer, the students who opened and close the season there have done the best musical.