A detailed analysis was conducted of the difficulty over time of the essay prompts for the English Composition Achievement Test (ECT) with Essay of the College Board. Differential difficulty was explored by considering whether the relationship between the reference groups of male and white students and the focal groups (female, American Indian, Asian American, Asian American with English-as-a-Second-Language, Black Hispanic American, and Hispanic American with English-as-a-Second-Language students) had remained constant over the 7 years studied (1983, and 1985 through 1990). To study the relationships between the ECT objective and the ECT with essay, linear regressions and conditional means of essay scores on objective scores were computed. For each comparison, difference lines for regressions and conditional means were plotted to identify years with aberrant differences. Differences were very consistent across the years, indicating that essay prompts did not generally cause groups to perform differentially. However, two essay prompts that may have caused differential performance were identified. Five tables and 17 graphs present analysis data. There is a 12-item list of references. Appendix A contains an additional 27 tables and 18 graphs. Appendixes B and C contain sample prompts. (Author/SLD)