This study compared 15 classes of freshman composition taught by the Aims approach, which stresses the different expressive, literary, persuasive, exploratory, scientific, and informative aims of writing which govern the writer's choices relative to author, audience, subject matter, and language and 16 classes taught by a traditional Modes approach, which stresses techniques relative to the mode of exposition and other modes of discourse. A standardized objective test and randomly drawn essays were used as pre- and post-measures. While recognizing that recent research has demonstrated that satisfactory reader reliabilities for the test essay can be obtained, this investigation raises the question of validity of the impromptu essay as an achievement measure, and thus the validity of results in such research studies. Recommendations for seriously modifying the nature of the test essay are given. (Author/RB)