This volume contains five papers from the conference in honor of Professor Dale T. Mortensen of Northwestern University, who has been the world leader of labor search theory for almost 40 years. Search theory has been developed to be a leading framework of analysis of questions in labor economics, industrial organization and macroeconomics. These include the research in economic growth, business cycles, monetary theory, wage and price dispersion and changes as well as employment mobility. Recent advances in theoretical and empirical research in all these topics adopt the search frictions as the basic framework. In this volume three papers focus on labor search theory and two are empirical. Shimer characterizes the wage dispersion in a model with search on-the-job using the strategic wage bargaining framework. Gaumont, Shindler, and Wright study the equilibrium wage dispersion in a posting wage equilibrium model where workers have ex-ante or ex-post heterogeneous preferences for jobs. They demonstrate that the wage dispersion critically depends on the information and the source of preference heterogeneity with respect to jobs. Shi uses the "directed search" framework to analyze the wage distribution in a model where workers have different levels of skills and each employer has one position to fill. Shi shows how the search friction and coordination difficulty due the strategic decisions of workers and firms may lead to equilibrium where wages may be higher for less skilled workers. Finally, there are two empirical papers. Jolivet, Postel-Vinay, and Robin use the Burdett-Mortensen model to test and interpret the link between wage dispersion, labor turnover and individual wage dynamics based on panel data from ten European countries and the US. Shimer's (2005) claim that the Mortensen-Pissarides model is not consistent with the macrodata is reconsidered by Yashiv. He shows that a more complex version of the model is fully consistent with the high persistence and volatility in macro labor variables observed as well as the negative correlation between vacancies and unemployment.