There is no one theory of migration that can fully explain why someone would choose to emigrate. Each theory may provide some explanation for the reason of migration, but no one theory can fully explain migration. There are three main schools of theories when it comes to migration: functionalist theory, migration as a social process, historical structural theory. The two most popular functionalist theories are neoclassical theory, alternately referred to as push-pull analysis, and the new economics of labor migration.

Push-pull analysis considers migrants to be unattached individuals making choices based solely on rational cost-benefit analysis. This theory of migration analyzes the potential difference in wages in different countries. Neoclassical theory does not account for any influence the family may have over a migrant, or a family migrating together. The migrant best subject to neoclassical analysis would be a single worker looking for higher wages.

The second functionalist theory is new economics of labor migration. There are two major differences between the two functionalist theories: first, as opposed to neoclassical theory, in the new economics of labor migration, wages are not the only determinate in an economic analysis, and second, the family is considered a strategic unit, as opposed to not being considered at all. An economic analysis of the benefits and drawbacks of migration would include factors such as credit availability, or access to loans, under the new economics of labor migration. Many individuals will migrate to a country with similar wages, though their movement is worthwhile as they can build credit or take out a loan. This is popular amongst those who wish to start a business, but cannot afford to just by working in their home country. Both functionalist theories do not account for any social influences in the migration process, and are thus incomplete explanations.

The second main school of thought used to explain why people migrate, is migration as a social process. Considering migration as a social process, focuses on the social pressures individuals feel to migrate. A theory within the school of migration as a social process is network theory. Network theory states that once one person migrates to a certain location, all migration from the same area becomes easier. The original migrant provides information and reassurance that migration to that destination is safe. A migrant experienced in migrating to a specific area can give advice as to where to seek employment, or where to live in the receiving country. The theory states that networks form, of migrants coming from and going to the same place, which aids in perpetuating migration.

Historical structural theories analyze macro structures and broad forces that affect migration. One area greatly analyzed by historical structural theories is neoliberalism. Neoliberalism, and corporate globalization results in displaced people, raising the possibility of migration. Individual migrants are not considered by historical structural, only large agency is studied by these theories.

Each theory concentrates on one area of motivation for migration. Migration theories are probabilistic, not deterministic, meaning that these theories can only state the most likely reasons for any individual to migrate, and not determine why. For this reason, every theory surrounding migration is incomplete and wrong, though each theory has merit and can be used to possibly explain an aspect of a migrant's motivation.