This is a microeconomic theory book designed for upper-division undergraduate students in economics and agricultural economics. Basic introductory college courses in microeconomics and differential calculus are the assumed prerequisites. The last, tenth, chapter of the book reviews some mathematical principles basic to the other chapters. All of the chapters contain many numerical examples and graphs developed from the numerical examples. The ambitious student could recreate any of the charts and tables contained in the book using a computer and Excel spreadsheets. There are many numerical examples of the key elements of marginal analysis. In addition, many practical examples are taken from the real world to illustrate key points.