"Transforming Science Assessment: Systems for Innovation," is a series of resources designed to provide state education leaders with: (1) Information about how states are currently pursuing statewide assessment systems in science; (2) Analyses of what features influence different approaches, with an eye to supporting state leaders as they make their own decisions regarding science assessment systems; (3) Detailed state profiles that highlight how and why some states have made decisions regarding designing and enacting different examples of systems of assessment; and (4) A how-to guide for policymakers looking to enact systems of assessment in science. This brief describes some of the ongoing efforts in states across the country to develop and enact assessment systems in science and to provide state and district leaders with assessment system models to consider as they implement new science standards. The brief focuses on two primary models that are emerging across state and district efforts: (1) State-led assessment systems, and (2) Distributed assessment systems.