This randomized, controlled trial was designed to document the effectiveness of Child FIRST (Child and Family Interagency, Resource, Support, and Training), a home-based, psychotherapeutic, parent–child intervention embedded in a system of care. Multirisk urban mothers and children, ages 6–36 months (N = 157) participated. At the 12-month follow-up, Child FIRST children had improved language (odds ratio [OR] = 4.4) and externalizing symptoms (OR = 4.7) compared to Usual Care children. Child FIRST mothers had less parenting stress at the 6-month follow-up (OR = 3.0), lower psychopathology symptoms at 12-month follow-up (OR = 4.0), and less protective service involvement at 3 years postbaseline (OR = 2.1) relative to Usual Care mothers. Intervention families accessed 91% of wanted services relative to 33% among Usual Care. Thus, Child FIRST is effective with multirisk families raising young children across multiple child and parent outcomes.