The thesis contains four independent essays that focus on economics of migration, education and labour. The first chapter joint with Anatole Cheysson focus on the effect of plurilingualism on brain drain. We study how foreign language proficiency affects brain drain by exploiting the heterogenous exposure of Albania to Italian television in the second half of the twentieth century. We document that Albanians’ exposure to the Italian TV signal was as good as random. We find that exposure to Italian TV led to a considerable increase in Italian proficiency rates and strongly increased the probability of migrating of highly skilled individuals while not affecting other skill groups. The second chapter, joint with Robert Gary-Bobo and Marion Gouss´e, studies the variation of the average treatment effect of education over time. To study the returns to degrees, we assume the existence of a finite number of latent types and estimate a finite-mixture model. We show that the expected real wages commanded by some higher-education degrees decreased in absolute terms in France, in the past two decades, and that this drop is not due to adverse selection. In the case of Master degrees, the student selection improved with time, in spite of the fact that the number of graduates increased substantially. The third chapter critically reviews the literature on the human capital of entrepreneurs exploiting insights derived from previous studies and stylized facts obtained from high-quality data in Denmark’s administrative register. The fourth chapter, co-authored with Leonardo Indraccolo and Jacek Piosik, studies the human capital determinants of entrepreneurship. Using Danish administrative data, we measure analytical and communication skills with high school grades in math and Danish language. We observe a positive complementarity between math and Danish language grades in predicting individuals’ self-selection into entrepreneurship. For the population of high performing math students, we exploit within-school, across-cohort variation in students’ exposure to peers whose father has a university degree in humanities to identify the effect of communication skills on the probability of becoming an entrepreneur. We find that the difference in entrepreneurship share between the most (90th percentile) and the least (10th percentile) exposed individual is 1.1 percentage points: 20% of the overall share of entrepreneurs in the economy.