This roadmap builds upon the work of the Institute of Education Sciences (IES) Statewide Longitudinal Data Systems (SLDS) Grant Program and the SLDS State Support Team (SST). The SLDS Early Childhood Integrated Data Systems (ECIDS) Toolkit--developed in collaboration by the SST, state representatives, and experts in the field--was created to support states working to develop an integrated early childhood data system. The ECIDS Toolkit focuses on the components of developing and implementing an integrated system and includes key indicators and elements of quality. The toolkit notes the importance of linkages to and alignment with K-12 data systems and beyond. This document takes this work further by focusing on high-quality linkages between early childhood and K-12 data systems. This document is aligned with the SLDS ECIDS Toolkit in many areas, particularly data governance, data use, and stakeholder engagement. (author abstract)