Given that youth of color face increased risk for delinquency and the centrality of family relationships varies across cultures, it is possible that parent-adolescent relationships play a more salient protective role against delinquency for certain racial/ethnic groups. The present study examined the link in a diverse sample of at-risk adolescents to determine whether the associations between parent-adolescent relationship quality and parent knowledge of their adolescents and delinquency differs among Latinx, Black, and White youth. Participants were 1050 adolescent-parent dyads from the Longitudinal Studies of Child Abuse and Neglect (LONGSCAN) who completed study measures when adolescents were 14 and/or 16 years old. Participants were diverse and approximately one-half were female. When youth were 14, parents reported about the quality of their relationships and involvement with adolescents, as well as their knowledge and tracking of their adolescents’ whereabouts and activities. Adolescents reported their past-year disruptive behaviors/conduct problems when they were 14 and delinquent behaviors when they were 16. Multiple regression analyses were conducted to examine the associations between age 14 parent- adolescent relationship quality and age 16 delinquency. Interactions were tested to determine if this association was moderated by race/ethnicity and simple slopes tests were conducted to probe significant interactions. Adolescent sex (male/female), family poverty, age 14 disruptive behavior/conduct problems, parental involvement, and adverse childhood experiences were controlled in all analyses. Higher parent-adolescent relationship quality was significantly and independently associated with less delinquent behavior but parental knowledge was not significantly associated with delinquent behavior. Significant interactions revealed that the association between parent-adolescent relationship quality and delinquent behavior was significantly moderated by race/ethnicity, such that higher parent-adolescent relationship quality was associated with less delinquent behavior for Latinx adolescents but this association was not significant for adolescents from White, Black, or mixed/other, races/ethnicities. The association between parent knowledge and delinquent behavior was not moderated by race/ethnicity. Our findings indicate that parent-adolescent relationship quality is especially salient among at-risk Latinx adolescents, relative to at-risk adolescents from other racial/ethnic groups. Culturally responsive interventions for delinquency in families of Latinx adolescents should emphasize to parent-adolescent relationships.