Data Cooperatives are a group of individuals or organizations that pool their data for mutual benefit. They serve many purposes, including protecting sensitive information, generating data-driven insights, and voluntarily sharing data for the social good and/or economic return to their members. This handbook is a hands-on guide for groups interested in forming a data cooperative. The process is laid out in four steps: determining if data co-ops are the right model for you, identifying the value proposition, designing the governance architecture, and creating a data infrastructure. The handbook includes case studies, tools, and links to further reading and resources to guide groups through a participatory co-design process and develop a data cooperative model that is right for them.