The energy intensity of data centers means that energy efficiency improvements have the potential to deliver substantial energy and cost savings to an organization. There are dynamics unique to data centers that create a set of underlying drivers, stakeholders, and barriers to data center energy efficiency projects that are distinct from energy efficiency projects generally. The Data Center Accelerator Toolkit collects guidance, factsheets, best practices, and other resources to help navigate these dynamics, based on the work of DOE's Better Buildings Data Center Accelerator. This toolkit addresses specific barriers and solutions for energy management in 5 primary data center types, including real-world examples for each.