This evaluation compared the efficiency and effectiveness of Functional Family Therapy-Child Welfare (FFT-CW®, n=1625) to Usual Care (UC: n=2250) in reducing child maltreatment. FFT-CW® is a continuum of care model based on the family’s risk status. In a child welfare setting, families received either UC or FFT-CW® in a quasi-experimental, stepped wedge design across all five boroughs of New York City. The families were matched using stratified propensity scoring on their pre-service risk status and followed for 16 months. The ethnically diverse sample included African American (36%), Asian (4%); Hispanic (49%), and Non-Hispanic White (6%) or Other (6%) participants. Referral reasons included abuse or neglect (57.4%), child service needs (56.9%) or child health and safety concerns (42.8%). Clinical process variables included staff fidelity, service duration, and number of contacts. Positive outcomes included whether all clinical goals were met and negative outcomes included transfers, outplacement, recurring allegations and service participation within 16 months of the case open date. Families receiving FFT-CW® completed treatment more quickly than UC and they were significantly more likely to meet all of the planned service goals. Higher treatment fidelity was associated with more favorable outcomes. Fewer FFT-CW® families were transferred to another program at closing, and they had fewer recurring allegations. FFT-CW® had fewer out-of-home placements in families with higher levels of risk factors. The FFT-CW® program was more efficient in completing service, and more effective than UC in meeting treatment goals while also avoiding adverse outcomes.