The Test of Written English (TWE), administered with certain designated examinations of the Test of English as a Foreign Language (TOEFL), consists of a single essay prompt to which examinees have 30 minutes to respond. Questions have been raised about the comparability of different TWE prompts. This study was designed to elicit essays for prompts that differed both in subject matter (topic) and in level of explicitness with which the essay task was presented (topic type). Eight different prompts were spiraled worldwide at the October 1989 TOEFL administration, with each prompt eliciting approximately 10,000 essays. Results of the analyses indicated that there were small differences among the prompts. The most notable differences were obtained among the scores for topics using the most explicit comparison. Across all the prompts, the chart-graph topic with the explicit comparison statement produced the highest mean scores. Because it was the first study to focus on the comparability of prompts in a major testing program, the authors had difficulty making definitive statements about the meaningfulness of the obtained differences. Such differences may warrant further consideration by the TOEFL program. Two appendixes present prompts and scoring guidelines. Fifteen tables present analysis results. (Contains 17 references.) (Author/SLD)