This paper examines the effectiveness of process writing instruction in English as a second language to foster contextualized situated learning of adverbial clauses of contrast (e.g., "although, even though, however, nevertheless, in spite of, despite, on the other hand"), as demonstrated in a group of six Brazilian upper-intermediate students of English for Special Purposes (ESP), all executives at a multinational company. The students' objective was better use of alternatives to "but" in written business communication. The report chronicles the development of a needs assessment form and elicitation of student views and goals, describes the process writing approach and its use in second language learning, compares Portuguese and English use of adverbial subordinate clauses of contrast, describes classroom procedures and activities, and evaluates results. Students pointed to the consistency of this approach with the principles underlying the ESP program (situated learning and communicative language teaching), and were able to identify their own progress. Their speech was found to be better organized and their ideas were expressed more accurately, appropriately, and coherently. The method is recommended. Materials documenting the classroom approach are appended. Contains 33 references. (MSE)