The Association of American Medical Colleges is conducting research to develop, implement, and evaluate a Medical College Admission Test (MCAT) essay testing program. Essay administration in the spring and fall of 1985 and 1986 suggested that additional research was needed on the development of topics which elicit similar skills and meet standard criteria for overall difficulty. Testing of essay prompts differing in focus and length of response was undertaken with the Fall 1986 MCAT administration. Some examinees responded to a 45-minute and a 15-minute essay, while others wrote two 30-minute essays. The 45-minute and 30-minute topics led to papers of notably different quality levels. The 45-minute response period allowed for: (1) fuller treatment of issues and more complete argument development; (2) better demonstration of skills involved in organizing and presenting ideas and sustaining a line of reasoning; (3) testing of higher level writing and analysis skills, and (4) addressing the objectives of the MCAT writing assessment. The 30-minute prompts produced papers with simplistic argument statements and an increased number of surface errors. The Advisory Committee to the MCAT Essay Pilot Project judged concerns about the 30-minute essays to be too marked to promote the use of 60-minute forms and felt the 45-minute response period gave the examinees an important opportunity to plan, organize, and execute a thoughtful essay. (BAE)