Rapidly changing technology, the globalization of markets, and the declining role of unions are just some of the factors that have led to dramatic changes in working conditions in the United States. Little attention has been paid to the difficult measurement problems underlying analysis of the labour market. This text aims to help fill this gap by exploring key theoretical and practical issues in the measurement of employment, wages, and workplace practices. Some of the chapters explore the conceptual issues of what is needed, what is known, or what can be learned from existing data, and what needs have not been met by available data sources. Others make innovative uses of existing data to analyze these topics. Also included are papers examining how answers to important questions are affected by alternative measures used and how these can be reconciled.