Online peer assessment is an innovative evaluation method that has caught both educators' and practitioners' attention in recent years. The purpose of this study was to develop relevant questionnaires for teachers to understand student self-efficacy and motivation in online peer assessment learning environments. A total of 205 college students with experience in online peer assessment participated in this study. Two questionnaires measuring students' online peer assessment self-efficacy (OPASS) and their motivations in online peer assessment learning environments (MOPAS) were developed. The former included three self-efficacy scales: evaluating, receiving and reacting. The latter included two scales: intrinsic motivation and extrinsic motivation. Through factor analysis, both revealed highly satisfactory validity and reliability in assessing students' self-efficacy and motivation in online peer assessment learning environments. Moreover, the students' responses also showed that they were highly confident and strongly intrinsically motivated when participating in an online peer assessment learning environment. Finally, the interplay between the scales of OPASS and those of MOPAS was explored and the reciprocal relationship between students' self-efficacy and motivation in an online peer assessment learning environment was also highlighted. (Contains 5 tables.)