Optimization in Microeconomics is a mathematical economics textbook that synthesizes what the reader knows about mathematics and economics. The exercises in the book ask readers to translate verbal descriptions of an economic problem into mathematical terms for use with optimization techniques to analyze and then translate the mathematical answers back into economic language. The optimization topics include functions of one variable, two variables, several variables, constrained optimization, and finally duality. In each case, the reader is asked to find optima, solve comparative statics problems, and to apply the Envelope Theorem. These last two topics are treated as central and are included from the beginning whereas other books view them as advanced topics. Optimization in Microeconomics is intended for a one-semester course in mathematical economics for undergraduates. Readers should already have seen some microeconomics and partial derivatives of functions of several variables.