This thesis studies how labor market institutions affect the careers of workers. To do so, I exploit the availability of Spanish Social Security data on workers' labor histories. Chapter 1 introduces the topic and presents an overview of the results of this thesis. Chapter 2 studies the impact of these regulations. In particular, it examines the effect of firing costs on human capital accumulation, cyclicality of job creation, and persistence of job loss. Chapter 3 presents macroeconomic evidence that the correlation between productivity and employment is negative in southern European countries, and assesses the role of two-tier labor markets in generating that correlation. Chapter 4 documents the determinants of becoming self-employed in labor markets characterized by high unemployment and low job stability.