In 1568, a group of Mexican mulatos unsuccessfully petitioned the Spanish crown for a license to build a hospital. The mulatos’ petition, however, is an important document that speaks to the legal avenues Afro-Mexicans explored in the mid sixteenth century in their attempts to improve their social position. Through an analysis of how the petition process played out, this article demonstrates how that process epitomized the growing limits placed on Afro-Mexican autonomy by colonial administrators. I contend that this case attests to the difficulties Afro-Mexicans continually encountered in their efforts to establish safety nets through such institutions as hospitals and cofradías, following the example of other colonial subjects. Over time, however, the mulatos’ attempts to institutionalize their privileges as permanent fixtures of colonial society, for example, in petitioning to establish a hospital, intensified the opposition of local royal authorities. I also argue that the petition reveals a Mexican mulato community taking form as a common goal brought the mulatos together, setting in motion a process of community-building through petitioning. Finally, the petition process allows us to see how mulato-ness was understood at the time, broadening our understanding of the category at the time as well as its transformations. The article thus contributes to the study of Afro-Mexicans’ use of the Spanish legal system in the mid sixteenth century, as well as their engagement with the Spanish petition system, two topics that have received little scholarly attention.