The predominantly 18th Century tradition of Casta Paintings has received little attention from art historians except in recent years. Casta Paintings generally appear in groups of sixteen portraits that trace the complex racial mixing or mestizaje of the people of New Spain. Each painting depicts a couple along with one or two children. Above the family appears an inscription describing the ethnoracial make-up of the mother, the father, and the child(ren), usually in the form of "A Spanish father and an African mother produces a Mulatto child (Espanol y Negra produce Mulatto)." In addition to showing ethnoracial categories and progressions, the paintings suggest typical clothing for different social classes, reveal details of architectural space and home life, and present meticulous depictions of everyday objects, native flora and fauna, and foodstuffs. They are, in short, a marvelous catalog of the Spanish fascination with ethnorace and of daily life for different social and ethnoracial classes during the colonial period. 

While the Casta Paintings generally suggest the fascination with race and limpieza de sangre (purity of blood) that characterized colonial Spanish mentalities, their use and purpose for production remains uncertain. In their forewords to Maria Concepcion Garcia Saiz's pictorial exploration of Casta Paintings, Las Castas Mexicanas,  Roberto Moreno de los Arcos, Diego Angulo Iniguez, and Miguel Angel Fernandez outline three of these different perspectives on the origins and purposes of Casta Painting. They describe the tradition respectively as an example of Enlightenment perspectives, a form with essential ties to Spanish artistic demand, and a decidedly New World form. Each of these views offers an important perspective on the Casta Painting tradition and helps to reveal its depth and diversity. 
 
In his foreword to Las Castas Mexicanas, Roberto Moreno de los Arcos articulates one of the most common explanations for the proliferation of Casta Paintings during the 18th Century. He links the classifying urge behind the paintings to the broader Enlightenment emphasis on classification and organization. De los Arcos suggests that the meticulous mapping of human ethnoracial characteristics, daily activities, and indigenous flora speaks not only to the Spanish fascination with race, but also to the leading philosophical and scientific preoccupations of the time. Ilona Katzew, in her article "Casta Painting: Identity and Social Stratification in Colonial Mexico", quotes Viceroy Manuel Amat y Juniet who commissioned a series of Casta Paintings in order to "contribute to the formation of the Natural History Collection" (Katzew 1996, 13). Amat y Juniet reflects the growing commitment to science common during the period of the Enlightenment. His words and the evidence of the paintings themselves suggest that the mentality of the Enlightenment strongly influenced the style and creation of Casta Paintings.

Iniquez also invokes the roughly contemporary Costumbrismo period in Spanish art to describe the Casta Paintings. Costumbrismo refers to a trend in Spanish art, especially literature, that represented daily life and ordinary circumstances. In Spain, Costumbrismo had roots in the 16th and 17th Centuries and grew to full power during the first half of the 19th Century. Thus artists in New Spain who had trained in Spain would be familiar with the tools of Costumbrismo. The fascination with familial scenes, local flora, and daily life so clear in Casta Paintings possiblly corresponds to a similar attention to the everyday in contemporary Spanish art. 

"To class it as a mere export product, an overseas souvenir, would be exaggerated and hasty. Naturally, the clientele would have been mainly Spanish (a Mestiso of the times would hardly be in a position to purchase oils); but it is very difficult to accept the notion that this body of work, with so much local color and such complexity of expression in terms of information imparted, could be rooted in an overseas market's nostalgia." (Foreword Fernandez, 20)

Each argument for the source of Casta Painting holds important information about the genre. It cannot be understood without recognizing its position in contemporary philosophical, scientific, and artistic traditions. Nor can it be separated from the interwoven history of Spain and New Spain during the colonial period. It reveals the fascinations and preoccupations of the era and offers insight into the construction of ethnorace in colonial times.