A growing number of communities are convening representatives from diverse sectors, including government, philanthropy, schools and nonprofits, to tackle entrenched social problems. Often called “collective impact” initiatives, these efforts move beyond traditional collaboration—by clearly defining communitywide goals and performance measures and carefully coordinating program strategies—in an attempt to produce a collective impact that no single organization could achieve on its own. By all accounts, the shared collection and use of data is central to collective impact efforts. But, to date, there has been little guidance for communities about how to make it happen. Collective Ideas to Collective Impact: A Guide to Data Collaboration in Communities taps the experience of two leading initiatives to provide concrete advice about planning, developing, launching and using a collaborative data system. Drawing on interviews with stakeholders in Boston and Omaha, as well as literature in the burgeoning fields of collective impact and shared measurement, the Guide offers step-by-step guidance for local officials, schools district leaders, nonprofit directors, funders and staff of intermediaries who are involved in collective impact efforts around the country.