Active Learning is becoming a standard method of delivering instruction in mathematics courses across the country. Researchers, administrators, policy makers, and instructors all need access to valid means of measuring practices used in the classroom. Drawing on the Postsecondary Instructional Practices Survey, the Student Postsecondary Instructional Practices Survey in Mathematics (SPIPS-M) was developed to measure the undergraduate student perspective of active learning. Factor analysis from 10 institutions (N = 16,495 surveys) supports a 4-factor model with a plausible theoretical foundation connected to the four pillars of Inquiry-Based Mathematics Education, by measuring the degree to which students perceive (1) their own engagement with meaningful mathematics; (2) collaboration to process mathematical idea; (3) participation and formation of community; and (4) contribution of their own ideas for immediate instructor feedback. The instrument provides a new mechanism for program evaluation and course formative feedback. Ultimately the SPIPS-M instrument will allow a better understanding of the nuances of student experiences in their mathematics courses.