What is the traditional name for the formal religious service held before some quinceañera receptions?

The traditional religious service held before some quinceañera receptions is called a Misa de acción de gracias.

The Spanish phrase means “Mass of thanksgiving.” In families that include a Catholic observance, the service gives the celebrant an opportunity to give thanks and receive prayers or a blessing. It is commonly followed by photographs, a procession, or the main reception.

This service is not identical to the birthday party itself. A family may hold a church service, a reception, both, or neither. Quinceañera customs vary widely across Latin America, the United States, and other places where the tradition is practiced.

The presence of a Mass reflects the strong Catholic influence historically associated with the celebration, but quinceañeras are also held by families from other Christian traditions and by secular families. The name should not be confused with a wedding Mass: the celebrant is marking a birthday and life transition, not entering marriage.