This study investigated the effects of teacher evaluation and student self-evaluation on student performance and attitudes. Participants were 189 Latvian high school students and their 6 teachers. The teachers were assigned to one of three treatment conditions: no evaluation, teacher evaluation, and self-evaluation plus teacher evaluation. All groups completed a 12-lesson instructional program on how to conduct experiments and produce research reports. The teacher-evaluation group received teacher evaluation on their initial research reports. The self-plus-teacher evaluation group self-evaluated their reports and received teacher evaluation on them. The no-evaluation group received no formal evaluation instructions. Students in the teacher evaluation and the self-plus-teacher evaluation groups received significantly higher ratings on their final projects. The no-evaluation group had more favorable attitudes toward the program than the other two groups. However, the self-plus-teacher evaluation group was significantly more confident of their ability to conduct future research experiments independently. (Contains 2 tables, 2 figures, and 28 references.) (Author/SLD)