With the growing shortage of time and money for writing new textbooks, particularly in the seldom-taught languages, there is a premium on making effective use of what already exists. A teacher has a choice, not only of accepting or rejecting materials, but adapting or rewriting them. (The fourth possibility is often viewed both as unjustifiably troublesome to the rewriter and an affront to the original author.) Of the dozens of language teachers with whom the author has spoken in the course of this study, he has found none who did not claim at least that he made some small changes or additions to his printed textbook; many make major changes. Under these circumstances, two points need to be emphasized: (1) various degrees of adaptation, augmentation, and rewriting form a continuum, at the far end of which stands the writing of original materials; and (2) before one can begin to adapt or augment or rewrite or write, and before one can even decide which of these four to undertake, it is necessary to evaluate what is already available. The present paper offers guidelines for evaluation, and outlines a general procedure for adaptation. (Author/AMM)