Abstract This cross-sectional study examined the association between parenting behavior, the parent–child relationship, and externalizing child behavior in families of children with mild to borderline intellectual disabilities (MBID). The families of a child with MBID and accompanying externalizing behavior problems (n=113) reported more positive discipline and physical punishment but less involvement, less positive parenting, less monitoring, a lower sense of parenting competence, less acceptance of the child, and less closeness to the child than the families of a child with MBID and no accompanying externalizing behavior problems (n=71). The parent–child relationship was most strongly associated with externalizing child behavior, over and above parenting behaviors. In addition, the parent–child relationship was found to be associated with parenting behavior, over and above the child's externalizing behavior. Our results highlight the importance of both the parent–child relationship and parenting behavior in connection with the occurrence of externalizing behavior problems on the part of children with MBID. Parenting behavior and the parent–child relationship may thus be promising targets for interventions with this group of children.