The practice of peer assessment has been widely recommended for use in physical education (PE) classes. However, it is unknown how accurately students in lower elementary grades can assess peers' performance. Therefore, this study examined the accuracy at which students in lower elementary PE perform peer assessments of a throwing skill. Students in first, second, and third grades conducted assessments of peers' overhand throw performance once per week for 4 weeks. Sessions were video recorded; a researcher viewed the videos and examined participants' assessments for accuracy. Results indicate that students in lower elementary grades can assess peers' performance with a relatively high degree of accuracy, with third graders performing significantly better than their younger counterparts. Results also show that students can accurately perform a peer process assessment immediately after a reasonably short assessment training session. It can be concluded that physical education teachers can implement peer process assessments with young students with the confidence that they will be conducted accurately.