This is a pilot study to determine whether an analysis of the Puerto Rican labor market experience can provide insights into the responsiveness of workers to changing labor markets and into the general experience of Hispanics in the U.S. labor markets. The project consists of three major tasks. First, a theoretical model of sectoral labor markets and labor mobility is developed. The model highlights the interdependency among primary and secondary labor markets while incorporating job search and non-labor force participation. Second, changes in the Puerto Rican labor market from 1950 to the present are examined with an eye towards establishing its relevance for understanding the experience of Hispanics in the United States labor market. This requires a detailed cross-section comparison of Hispanic sub-groups in the United States with the Puerto Rican labor force. Third, the project examines the cyclical and structural sensitivity of labor force participation to changing conditions. These comparisons will be of a time series nature and are disaggregated by ethnicity, gender and age.