ABSTRACT An ethnographic study done in Hidalgo County. Texas, among 25 Mexican American first-time mothers and fathers documented the presence of an intergenerational family ritual that facilitated adaptation to parenthood in 24 of the 25 families. La cuarentena is a family ritual of 40 days duration postbirth with cultural prescriptions for maternal food and clothing and for paternal role reversal. La cuarentena instills parental responsibility, incorporates individuals into the family, and integrates the family during this critical life-event of first birth. A thorough understanding of la cuarentena will assist nurses to enhance adaptation to parenthood for Mexican American parents.