Motivation and effort patterns associated with achievement on classroom assessments in middle-school science and social studies were studied with a sample of 223 8th graders in different classroom assessment environments. Classroom assessment environments were characterized by student perceptions of the importance and value of assessment tasks, perceived self-efficacy, and mastery goal orientations. It was expected that both classroom assessment environment and the particular assessment would be related to differences in motivation, effort, and their effects on achievement, even after controlling for prior achievement. The classroom assessment environment did make a difference in classroom achievement, with an effect size comparable to the effect for prior achievement. Motivational variables added to the prediction of classroom achievement after controlling for prior achievement and for classroom environment; perceived self-efficacy was the strongest motivational predictor. After controlling for background and motivation, effort variables did not predict additional variance in classroom achievement. Hypothesized differences in the prediction of classroom achievement between tests and performance assessments were not clearly evident.