This book is designed to help users with research questions or hypotheses that can be tested using census data. A prior acquaintance with demographic techniques is not required. The author shows how census data can be used to complement other data sources and can provide information on research questions which cannot be tested statistically. Using specific examples, the author illustrates the choices and constraints that researchers face, points out ways to code, clean and interpret the data, and provides the latest information on census geography, the undercount problem, question error rates, data products and plans for future US censuses.