Novice teachers struggle with assessing fundamental motor skills. With growing time constraints, not to mention the current COVID-19 pandemic, professional development needs to be streamlined, asynchronous, and online to meet the needs of current teachers. The purpose of this study was to test the feasibility and efficacy of the Motor Skill Assessment Program (MSAP) in increasing the assessment competency of the underhand roll among physical educators and to examine which factors associated with posttest assessment scores. Twenty-nine physical educators (female = 21, male = 8) completed the program. Paired sample t tests were used to determine the efficacy of the program in improving assessment accuracy from pretest to posttest. Associations between posttest scores assessed which factors predicted success within the program addressing feasibility. Program completion resulted in significantly better posttest assessment scores among participants. Guided practice attempts and average scores on guided practice tests correlated most strongly and positively with posttest scores. The assessment training program increased the assessment competency of physical educators. Guided practice and using practice tests best predicted participant learning. Now that the MSAP results with teacher learning and is feasible, this efficacy trial should be scaled up to feature a control group and more skills.