This chapter highlights a number of flaws with current practices in the measurement of recidivism and offers suggestions for improvements in the measurement, collection, and sharing of data related to the experiences of individuals returning to society from incarceration. Problems with current measures of recidivism include lack of precision, lack of standardization, and possible bias. Multiple, precise, and uniformly defined measures should be used. Measures that focus on reengagement with the criminal justice system are insufficient to gauge a reentering individual’s progress, which is likely to be incremental, will probably involve setbacks, and inevitably spans numerous policy areas. Instead of primarily emphasizing reentering individuals’ risks of recidivating, more attention should be paid to their needs, and to information about access to reentry resources to address those needs. Data sharing between different levels of government and policy domains, between custody and community, and across the public and nonprofit sectors can improve the delivery of resources and services, reducing waste and improving lives. Concerns about privacy and confidentiality, technological limitations, insufficient funding and capacity, and lack of motivation currently impede efforts to share and integrate data. With political will, support, and resources, obstacles to data sharing can be overcome.