The Population Registration Act of 1950 required that all inhabitants of South Africa be classified in accordance with their racial characteristics as part of the system of apartheid. Social rights, political rights, educational opportunities, and economic status were largely determined by which group an individual belonged to.

There were three basic racial classifications under the law: Black, White and Coloured (Mixed). Asian was later added as a separate classification as they were seen as having "no historical right to the country".

An Office for Race Classification was set up to overview the classification process. Classification into groups was carried out using criteria such as outer appearance, general acceptance and social standing. For example, it defined a "white person" as one who "in appearance is obviously a white person who is generally not accepted as a Coloured person; or is generally accepted as a white person and is not in appearance obviously a white person." Due to the fact that some aspects of the profile were of a social nature, reclassifications were not uncommon, and a board was established to conduct that process.

This law worked in tandem with other laws passed as part of the apartheid system. Under the Prohibition of Mixed Marriages Act of 1949, marrying a person of a different race was illegal. With the enactment of the Immorality Amendment Act (Immorality Act) of 1957, it also became a crime to display intent or interest in conducting a relationship with a member of a different race.

The South African Parliament repealed the act on June 17, 1991.