Urban American Indian (AI) adolescents are more likely than non‐Natives to have early sexual debut, teen pregnancies, sexually transmitted infections, and inadequate sexual health information. A RCT in three Arizona cities, with 585 parents of urban AI adolescents, tested whether a culturally tailored parenting intervention for urban AI families, Parenting in 2 Worlds (P2W), increased parent–adolescent communication about sexuality, compared to an informational family health intervention that was not culturally tailored. P2W produced significantly larger increases on two measures: communication about general sexual health and about sexual decision‐making. The desired effects of P2W on the first measure were stronger short‐term for cross‐gender dyads, while for the second measure, they were stronger long‐term for both mothers and fathers of adolescent sons.