Mastery learning is an instructional method based on the idea that students learn best if they fully understand, or master, one concept before moving on to the next and has been shown to be extremely effective in math and science curricula. Competency-based grading is an evaluative tool that allows the faculty member to determine the level of mastery students must achieve for a passing grade and lets the student choose whether he or she wants to work beyond this base level of mastery for a higher grade. This article provides a guide to facilitate the implementation of this complementary set of instructional and assessment tools specifically in a sophomore-level Organic Chemistry course, but with the potential for general application in many subject areas. (Contains 6 tables and 3 figures.)