In this study, peer assessment was applied in assessing elementary science teaching skills. Preservice teachers taught a science topic as a team to their peers in an elementary science methods course. The peers participating in the science lesson assessed teacher-groups' elementary science teaching skills on an assessment form provided by the instructor. The peer scores were analyzed by means of descriptive statistics and linear regression. To analyze the reliability and validity of peer assessment, t-test statistics and one-way ANOVA (analysis of variance) procedures were applied. The results revealed that, although peer scores were considerably higher than the instructor scores, they significantly correlated with the instructor scores. Reliability analysis revealed that the students assessed their peers' science teaching performance reliably.