We report on the differences in mathematics learning environments in classes taught by certified Elementary Math Specialists (EMSs) (n = 28) and their peers (n = 33) as determined by observations of instruction. We used path analysis to examine how variables such as mathematical knowledge for teaching, beliefs, and background characteristics were related to the learning environment. We used the Classroom Learning Environment Measure (CLEM) observation protocol, which attends to aspects of mathematics lessons such as opportunities for students to justify their reasoning and attend to mathematical concepts. Our analysis revealed that learning environments incorporating such elements were significantly more prevalent in classes taught by EMSs, and that there were two paths indicating mediation effects on the relationship between EMS status and learning environment. One path was related to teachers' beliefs about the primacy of computation in learning mathematics; the other path was related to teachers' mathematical knowledge for teaching and their beliefs about the extent to which mathematical knowledge is constructed by the learner. We share implications for EMS programs and recommendations for future research on the impact of EMSs in elementary schools.