The Early Childhood Integrated Data System Guide is one part of the SLDS Early Childhood Integrated Data System Toolkit, which was originally created in 2011 to support states working to create an Early Childhood Integrated Data System (ECIDS). Since then, states have used the Toolkit for purposes beyond the initial intent, including state planning for the ECIDS; education for other sectors (e.g., K12, workforce, and university partners); support for state conversations as a communication tool/resource; and identification of strengths to promote within the state and potential weaknesses requiring additional support. The revised SLDS Early Childhood Integrated Data System Toolkit now takes a broader focus beyond initial planning for an ECIDS to include implementation and continuous improvement. Based on seven components of ECIDS planning and development, the Toolkit was designed for use by any state regardless of where it is in the process of developing an ECIDS. The seven components are: A. Purpose and Vision; B. Planning and Management; C. Stakeholder Engagement; D. Data Governance; E. System Design; F. Data Use; and G. Sustainability. As depicted in figure 1, these components are not linear. States often start where they have current capacity and resources. In addition, each component has content related to aligning early childhood to P-20W+ (early childhood through workforce and beyond) statewide longitudinal data system (SLDS) efforts in the state. This guide offers practical suggestions and resources for each step in the overall process of integrating data across early childhood and connecting the data to a P-20W+ SLDS. (author abstract)