The study found that the use of holistic defenses did not affect conviction rates; however, it reduced the likelihood of a custodial sentence by 16 percent and expected sentence length by 24 percent. Over the 10-year period of this study, holistic defense in the Bronx, the site of this study, resulted in nearly 1.1 million fewer days of custodial confinement. Holistic defenses did not dramatically reduce recidivism, as some proponents have claimed. Its impact on the number and length of custodial sentences, however, suggests that it should be considered in discussions about how to address mass incarceration. Future research should examine the effects of the holistic model beyond the criminal justice system and in other jurisdictions. The Bronx in New York was selected for this study because holistic defense providers (the Bronx Defenders) and a traditional defender for indigent defendants (the Legal Aid Society) operate together in the same court system. Case assignment is determined quasi-randomly based on court shift timing. Using administrative data for just over 500,000 cases and a quasi-experimental research design, researchers estimated the causal effect of holistic defense on case outcomes and future offending. Study limitations are noted.