Opportunity NYC-Family Rewards was the first conditional cash transfer, randomized controlled trial for low-income families in the United States. From 2007 to 2010, Family Rewards offered 2,377 New York City families cash transfers that were conditional upon their investments in education, preventive health care, and parental employment. Their health and other outcomes were compared to those of a control group of 2,372 families. The experiment led to a modest improvement in health insurance coverage and a large increase in the use of preventive dental care. It improved parents' perception of their own health and levels of hope, mainly through improvements in reported financial well-being. While the program's impacts on physical health were weaker, our study might not have captured effects on chronic disease risk that take longer to accrue. In the context of New York City's operating social-safety-net programs, conditional cash transfers may have led to positive, albeit modest, improvements in the health of poor families.