A total of 341 Latvian students and eight teachers participated in this study of student self-evaluation and teacher evaluation. Students completed a 12-lesson teacher-directed instructional program on conducting and writing a report of their own experimental research. Sixteen classes were randomly assigned to one of four treatment conditions: (1) no in-program evaluation, (2) self-evaluation and revision at the research design and draft final report stages, (3) teacher evaluation and student revision at both stages, (4) self-plus-teacher evaluation and student revision at both stages. Students in the teacher-evaluation and self-plus-teacher evaluation conditions received significantly higher ratings from an independent rater on their final research reports. However, students under the self-evaluation conditions had greater confidence in their ability to conduct future experiments.