To determine the effects on test performance and test validity of releasing essay topics before a writing examination, researchers asked 300 prospective graduate students to write 2 essays, 1 on a previously unseen topic and 1 on a topic that was made available about 2 weeks before the test. Although for each of the 4 essay topics studied, performance was slightly better when a topic had been disclosed, overall analyses did not reveal any statistically significant effect of disclosure on test performance. Consequently, there was no detectable effect of disclosure on the relation of test performance to several independent indicators of writing skill. Limitations of the study are discussed in terms of its generalizability to a high-stakes testing situation and the extent to which it addressed both the positive and the negative effects of disclosure.A prevailing view among composition specialists is that writing is a process, one that entails complementary activities of prewriting and planning, drafting, writing, and revising (these activities are not, however, a neat sequence of stages; Flower &Hayes, 1980). Because traditional tests of writing usually allow enough time only for developing a first draft and not for any significant planning or revision, they may not adequately elicit all of the processes that writers typically employ, and therefore, they may not fully represent all of the important facets of writing proficiency. In other words, the test may suffer from a major source of invalidity-what Messick (1989) has termed construct underrepresentation. In more lay terminology, the kind of impromptu writing that is typically required for direct measures of writing ability does not represent real writing. As one graduate faculty Requests for reprints should be sent to Donald E. Powers, Mail Stop 17-R, Educational Testing Service, Rosedale Road, Princeton, NJ 08541.