This is a hands-on guide for the growing number of researchers in organic chemistry, biochemistry, and molecular biology who would like to augment their experiments with theoretical calculations. Given the current availability of sophisticated software, non-quantum chemistry practitioners can obtain accurate computational results and save significant amounts of laboratory time. This book teaches the use of quantum chemical computer programs while side-stepping the complex mathematical details. The book focuses on what kinds of biological problems can be solved by quantum mechanical calculations and how to select the appropriate methods.