We report the results of an action research study in which a modified mastery-based learning approach was implemented in three undergraduate engineering courses: engineering statistics, LabVIEW programming, and environmental engineering. In this paper, we describe both the action research and the modified mastery-based learning approach that was implemented. Findings from the analysis of data on student performance, and student and faculty perceptions of the approach are presented. In addition, we discuss our recommendations for modifications to the approach that could be used in future implementations.