This examination of an evaluation of writing based on process rather than on product argues that one of the primary functions of evaluation as a part of teaching should be to diagnose the writing strategies that underlie a writer's current performance, not just textual problems. The first half of the paper discusses the various ways teachers use evaluation; the purposes for their extensive, detailed editing and elaborate comment on student papers; and the reasons that such dedicated responses so often fail. It then reviews the research in the area of defining and influencing writers' thinking strategies. The second half of the paper describes a study of how writers generate ideas that contrasted the verbal strategies of four "good" writers with four "poor" writers as they composed aloud by analyzing transcripts of their verbal protocols with regard to new idea generation and new idea source. A discussion of the results of the study reports that good writers generated new ideas in response to a rhetorical problem, while the idea source for poor writers was either in response to the topic itself or to a current element in memory. (AEA)