The main drive behind immigration is economics. People who leave their home countries because of the risk of being persecuted are refugees, not immigrants. Immigrants generally come in search of economic opportunity, although family is another major reason. The topic of economic costs and benefits associated with immigration is one possibility for a thesis paper, especially because modern immigration policy is heavily weighted toward finding workers. Economic incentives for immigration is another possible topic; a thesis on this topic could examine reasons -- such as poverty or inequality -- people want to leave their home countries and start a new life.
Immigration often becomes a politically charged issue. In some countries, the established population does not want to compete with immigrants for jobs. In other countries, some may fear that unchecked immigrant populations may contribute to crime or social discord. In the United States, many people feel the government does not do enough to enforce immigration laws. Immigrants, for their part, sometimes feel the established population is biased or prejudiced against them. The relationship between illegal immigration and nativist movements is one topic with potential because illegal immigration tends to carry significant backlash. The dynamics between legal immigrants is another interesting topic, as the Pew Research Center has found that many legal immigrants have concerns about illegal immigration.
Immigration is of some interest to sociologists. In the United States, a country with immigrants from all over the world, the vast majority of the second generation immigrant population speaks English instead of the language of their home country. In some European countries, there has been less success in getting the immigrant populations to adopt local cultural norms. The sociology of multiculturalism and assimilation provide many topics for a thesis on immigration. Linguistic assimilation around the world is one topic with potential, especially because levels of assimilation vary from country to country. Cultural tensions between immigrant groups and native groups in Europe is another topic with research potential, as European immigrants are often of different language and religious backgrounds than the native population.
Immigration law determines the role of immigrants in society. For legal immigrants, factors such as family, criminal history and employment determine an individual's ability to move to a new country. For illegal immigrants, the enforcement of immigration laws determines if it is possible to find work. The topic of immigration law enforcement could be used for a thesis on immigration, as the levels of enforcement vary from state to state and from country to country. The topic of immigration quotas also has research potential because many countries are desperate for immigrants with highly specialized skills.