This escudo de monja, or literally "nun's shield," was a type of devotional badge worn by nuns in New Spain (the colonial territories in North and Central America governed by Spain). These badges originated in response to reforms aimed at curtailing the luxury of convent life by banning the wearing of devotional ornaments made of gold, precious stones, or other valuable materials. In accordance with these reforms, yet also in defiance of them, the nuns instead wore elaborately painted badges such as this one, which were often the work of the finest artists of the period.

This work is one of the few surviving escudos painted on vellum, of which the Museum owns a second example, and it also retains its original tortoiseshell frame. Produced by one of the artists in the Lagarto family of painters, it is likely one of the earliest escudos known today.