Grounded in developmental and cultural-ecological perspectives, the current study examined trajectories of parent-youth conflict regarding everyday issues across adolescence and into young adulthood. Data came from 246 Mexican-origin families in the southwestern United States with younger siblings (51% female, M age = 12.8, SD = 0.58), older siblings (M age = 15.5, SD = 1.57), mothers (M age = 39.0; SD = 4.6), and fathers (M age = 41.7; SD = 5.8) and were collected at four time points over an 8-year period. Multilevel modeling analyses revealed linear declines in mother-youth and father-youth conflict across ages 12-22. Youth, but not parent, familism values were associated with variation in parent-youth conflict. This study extends understanding of culturally and developmentally salient processes of mother-youth and father-youth relationships in Mexican-origin families.