Beaver made his professional stage debut in October 1972, while still a college student, in "Rain", from W. Somerset Maugham's short story, at the Oklahoma Theatre Center in Oklahoma City, Oklahoma. After returning to Texas, he did a great deal of local theatre in the Dallas area, supporting himself as a film cleaner at a 16 mm film rental firm and as a stagehand for the Dallas Ballet. He joined the Shakespeare Festival of Dallas in 1976, performing in numerous productions. In 1979, he was commissioned by Actors Theatre of Louisville to write the first of three plays for that company ("Spades", "Sidekick" and "Semper Fi"), and was twice a finalist in the theatre's national Great American Play Contest (for "Once Upon a Single Bound" and "Verdigris"). Along with plays, he continued writing for film journals and for several years was a columnist, critic and feature writer for the National Board of Review of Motion Pictures magazine "Films in Review".