This study used an uncontrolled pre-post design in the context of a 16-week comprehensive school physical activity promotion (CSPAP) course to examine relationships between and changes in preservice classroom teachers' (PCTs; N = 103) efficacy beliefs about integrating movement in the academic classroom, willingness to integrate movement, and perceived barriers to movement integration. Efficacy beliefs were not correlated with willingness to integrate. Perceived barriers correlated with willingness to integrate at the beginning and end of the course and with efficacy beliefs at the beginning of the course. MANOVA with repeated measures indicated collective efficacy beliefs (i.e., beliefs about the capability of peers and practicing classroom teachers to integrate movement) strengthened and the number of perceived barriers decreased. Results highlight the relationship between perceived barriers and willingness to integrate movement and also suggest preservice programs could help to foster PCTs' collective efficacy and reduce perceived barriers, although experimental research is needed.