The Center for the Study of Social Policy (CSSP) and seven communities that have been leaders in developing early childhood systems have worked together to develop two tools described in this paper. The first is a set of Population-Level Outcomes and Indicators specifying the conditions of well-being for young children that communities seek to achieve, along with a short set of indicators that can be used to track progress towards those outcomes. The second is an Early Childhood System Performance Assessment Toolkit that describes four ways in which an effective early childhood system can contribute to improved outcomes, and identifies measures relevant to each of those four types of contribution. (author abstract)