All infants and toddlers need good health, strong families, and positive early learning experiences. Furthermore, young children benefit most from an early childhood system that is built through collaboration. These goals form the framework for a policy agenda that creates a comprehensive range of services and supports that honor the needs and choices of families for their children. This brief describes a self-assessment toolkit that draws on research on effective policies and best practices to help states evaluate progress toward building an effective early childhood system, and to set priorities for improvement. The toolkit will guide state policy leaders through a series of questions that will prompt them to collect data on how infants and toddlers are doing in their state and to analyze existing state policies and funding choices. [The toolkit is available online at: www.zerotothree.org/satool2015.]