Effortful control (EC) is a regulatory capacity that refers to children's ability to inhibit a dominant response to perform a subdominant response. Although attempts have been made to identify early predictors of children's EC, the confluence and interaction of child‐, familial‐, and community factors has not been pursued adequately. This study investigated how predictors from different aspects of children's rearing environment interacted to predict later EC. In a sample of 88 primiparous women with elevated depressive symptomotology and low household income, we examined how children's own psychobiology (baseline cortisol), familial relationship (mother–child attachment), and community resources (social support) at 17 months independently and jointly predicted EC at age 5. Our results showed that, controlling for maternal depressive symptomotology and household income, predictors from child‐, familial‐, and community‐aspect function integratively, rather than independently, in predicting later EC. Specifically, within the context of a secure attachment relationship, baseline cortisol positively predicts later EC only for children of mothers who reported low social support. Whereas within the context of an insecure attachment relationship, baseline cortisol negatively predicts later EC, regardless of the perceived social support levels. Our results highlighted the importance of taking into consideration predictors from multiple aspects for intervention designs.