The Spanish Colonial Casta System The Casta system of colonial Spain determined a persons social importance in old Mexico, and the church and government records of the times used over one-hundred diffrent terms to describe diffrent racial categories. The names Peninsular, Criollo, Indio and Negra describe persons of "pure" racial ancestry, whereas names such as Mestizo, Mulatto, and Zambo, in addition to many other terms, describe the "mixed-blood" children resulting from inter-racial marriages. Definitions of the main casta categories of colonial Spain follow. Españoles were persons of pure Spanish ancestry. Those born in Spain were Peninsular , and those born in the Americas were Criollo/Criolla . A one-eight rule existed wherein Criollo status could be attained by those of mixed blood who had an eighth or less indian ancestry. For example, the child of a Castizo parent (3/4 Spanish, and 1/4 Indian) and a Criollo parent would be Criollo. This one-eighth rule did not apply to those with some African ancestry.

Indios/Indias were persons of pure Indian Ancestry. It was illegal to enslave Indians, but Indians could be forced to work on government projects, such as roads, forts and churches, such work being viewed as a form of taxation. Because there was no separation between church and state in colonial Spain, work performed for the church was the same as work performed for the government.

Mestizos/Mestizas had one Spanish and one Indian parent. The term implied illegitimacy in the early days of the Spanish conquest, but mixed-race children of subsequent generations who were born in wedlock were generally assigned either Indian or Spanish identity (i.e., indio or Criollo), depending upon which culture they were raised in.

Castizos/castizas had one Mestizo parent and one Spanish parent. The children of a Castizo and an Españole (Criollo or Peninsular) were generally accepted as Criollo.

Cholos/Cholas had one Indian parent and one Mestizo parent. Cholo is also the word for coyote.

Mulattos/Mulattas had one Spanish and one Black parent. If mulattos were born into slavery (i.e., their mother was a slave), they would be slaves also, but if their mother was free, they were free. If one parent was mulatto and one Spanish, the child was a quadroon , and there existed a variety of other terms for different percentages of black ancestry. For persons with a complex racial heritage for which a simple term did not exist, the term pardo/parda might be used.

Zambos/Zambas had one Black and one Indian parent.

Negros/Negras were persons of pure African ancestry. Because it was illegal to enslave Indians, only those of African ancestry could be called a slave. Realistically though, many Indians were forced to work church and government projects, but such work was considered taxation, not slavery. Although most of the colonial slave trade was controlled by Portugal, it is estimated that Spain still imported at least 200,000 black slaves into Mexico, most arriving through Veracruz on the eastern coast. Even though it was illegal since the early days of the Spanish conquest to enslave the Indian population, black slaves were still permitted, and slavery was not completely outlawed until Mexico's 1821 independance from Spain.