What factors affect the ways individuals participate in labor markets?New Developments and Research on Labor Markets (volume 4B) proposes answers to this and other questions on important topics of public policy. Leading labor economists demonstrate how better data and advanced experiments help them apply economic theory, yielding sharper analyses and conclusions. The combinations of these improved empirical findings with new models enable the authors of these chapters to reveal how labor economists are developing new and innovative ways to measure key parameters and test important hypotheses.