Abstract. In a series of four studies, I developed and found evidence supporting the validity of a new measure, the Motivation to Participate in Psychological Research Scale (MPPRS). Based upon the tenets of Self-Determination Theory and aimed at measuring motivation in undergraduate students, the scale demonstrated a three-factor structure in exploratory and confirmatory factor analyses (Study 1: N = 238, Study 2: N = 264, Study 3: N = 297). Factors corresponded to autonomous motivation, controlled motivation, and amotivation. Preliminary evidence supported the validity of MPPRS scores, and subscales differentiated psychology majors from non-majors, as well as associated with the timing of research participation during the semester. Examining student motivation with the MPPRS has possible implications for data quality, as a moderator of research findings, and might be used to track changes in students’ interest regarding psychological research. However, future research is needed to assess the predictive validity of the MPPRS.