Migration of people from one country to another and their integration into the society of the destination country constitute a long and complex process. This process begins with the first plan of a person to leave her home country. It does not end until the immigrant stops assimilating and intensifying social networks to natives. In the introductory part of the dissertation an overview of the economic relevance of migration and integration shall be given. In four self-contained chapters aspects that have not gained much attention by economic research up to now shall be analyzed.How do migrants choose their destination country? In the second chapter, we analyze the effects of socio-economic and institutional determinants, especially labor-market institutions, on migrants' location choices. Based on a large data set constructed from micro-data for France, Germany, the UK, and the US, we study their decisions to migrate to one of the four countries using a Multinomial Choice framework. Our estimates confirm a number of conventional results, such as positive effects of wages and immigrant networks and negative effects of unemployment rates. In addition, we find that union coverage and unemployment benefits tend to have negative effects, while employment protection does not have a clear-cut impact on migration. There are indications of "insider-outsider effects". Also, good education and health systems tend to attract migrants, while generous pension systems deter them.Does Educational Choice Erode the Immigration Surplus? In most cases, immigration does not occur as a single, unexpected event. Thus, natives can take immigration into account when making their education decision. Analyzing the effects of immigration on native welfare, the adjustment of the native educational structure has to be considered. The third chapter shows that this decreases the positive effect of immigration on native welfare. Actually, it is not the ultimately realized immigration but the expectations which natives have on immigration that is crucial for their education decision. These expectations strongly affect native welfare. The higher expected immigration relative to realized immigration, the lower native welfare.High Unemployment in Germany: Why do Foreigners Suffer Most? In Germany, immigrant unemployment is not only higher than native unemployment. It also reacts more to changes in the situation on the labor market. Decomposing the gap between native and immigrant unemployment into a baseline and a labor-market situation component, I find in the fourth chapter that the unemployment rate of immigrants would lie at 5.6 percentage points for zero native unemployment (the baseline component of the gap). An increase in overall unemployment by 1 percentage point leads to a 0.7 percentage point higher increase in immigrant unemployment than in native unemployment (the situation component). The large part of this difference, about 3/4 of the baseline and 4/5 of the situation component, can be explained by differences in the endowments with classical human capital (educational degrees and experience) between immigrants and natives. Also controlling for country-specific human capital, particularly language skills, the situation component becomes insignificant and the baseline component again decreases by 1/2. Adding controls for social networks, the baseline effect also becomes insignificant. Thus, human capital and social networks can possibly fully explain the difference between native and immigrant unemployment in Germany.Why Applying Educational Requirements for Naturalization? Although naturalization is an important step towards the integration of immigrants, up to now there are very few economic papers on naturalization policy. In the fifth chapter the effects of skill requirements for naturalization are analyzed. These requirements affect the skill structure of the immigrant population in a country and also the welfare of natives, as long as the skill structure is connected with the fiscal balance of an immigrant. It is shown that there can be an optimal level of skill requirements for naturalization that is neither extremely high nor extremely low. In a further step the chapter analyzes how this optimal level is affected by other modes of action of naturalization policy. With regard to the children of immigrants this implies that a ius sanguinis legislation should be preferred to a ius soli legislation. However, as discussed in the chapter, there are also strong arguments for a ius soli legislation.
