A study examined use of prewriting techniques among 11 students of English as a Second Language (ESL), of varying language backgrounds, enrolled in a pre-freshman composition class. It investigated use of both prewriting strategies and invention techniques taught in class, looking at: (1) whether they would be used when not specifically required; (2) the relationship between the way a heuristic was taught and the way it was used; (3) variety and frequency of use; (4) relationship between native-language (L1) writing experience, second-language (L2) proficiency, and use of various techniques; and (5) how content generated by invention writing was incorporated into a draft. Data were gathered from students' pre-draft writing and first drafts of a total of 22 essays. Results indicate that ESL writers use various invention techniques productively, and that these were apparently unrelated to L1 writing experience or high L2 proficiency. However, L1 experience and L2 proficiency may have limited impact on specific use of the techniques. Subjects clearly preferred techniques that lend themselves to approximating and translating the inner dialogue of the composing process, and it appeared they instinctively adapted invention techniques to conform to the psychological reality of the composing process when the technique, as taught, varied from this. Pedagogical implications are examined. (MSE)