Enzymes are complex biological molecules capable of catalyzing chemical reactions with very high efficiency, stereo-selectivity and specificity. The study of enzymatically-catalyzed reactions gives insight into the study of organic reaction mechanisms in general, and into the topic of catalysis especially. This course explores the methods and frameworks for determining mechanisms of enzymatic reactions. These methods are based on a firm foundation of chemical kinetics and organic reaction mechanisms. The first portion of the course is devoted to enzyme kinetics and catalysis including discussions of transition state theory, structure-reactivity relationships, Michaelis-Menten parameters, pH-dependence of catalysis, and methods for measuring rate constants. As the course progresses, the concepts of mechanism and its elucidation is applied to specific enzymatic processes as we discuss reaction intermediates and stereochemistry of enzymatic reactions. Our discussions of modern methods include the use of altered reactants, including mechanism-based inactivators and genetically modified enzymes as tools for probing enzymatic reactions.