The article relates a fatal highway robbery near the mining town of Zacatecas, Mexico, on January 3, 1709, and the subsequent prosecution of the perpetrators in order to investigate the social and economic stratification and class dynamics and identities of the colonial society in New Spain in the early 18th century. Particular attention is paid to the situation of castas, mixed-race people in according to prevalent social and legal distinctions, their relationship to other marginalized people, such as poor Spaniards and Spanish-speaking native Americans known as ladinos, and their integration in Spanish-Mexican colonial society.