In a long rambling dissertation, Lawrence Langner, co-founder of the Theatre Guild, unfolds his practical advice for playwrights. He discusses how a writer needs to live and work, what makes a play, what sort of plot and characters the successful play must have, and the playwright's problems in production and rewriting. He analyzes the best approach to adaption and collaboration and touches on television writing. His approach is primarily that of the producer and his analysis of the themes and construction of plays might be considered by theatre historians to be generally sophomoric, if not soporific. But his successful-production-do's-and-don'ts are soundly rooted in the traditional forms of theatre and may be helpful to the beginning playwright. The one premise that Mr. Langner finds most valid is that the playwright must seek audience identification. This reader is inclined to feel that aiming for modern audience identification leads inevitably to those tedious suburban comedies about marital infidelity. However, for interesting sidelights on the habits of great writers -- O'Neill, Shaw, Sherwood, and Anderson- it is passable reading and supplies general information to the layman. Mr. Langner's traditional attitudes are worthy of attention.