The long-term goal of the State Systemic Improvement Plan (SSIP) and other federal and state early intervention and early childhood education initiatives is improved child and family outcomes. States play a critical role in supporting practitioners in the use of evidence-based practices to improve child and family outcomes. When practitioners implement evidence-based practices as intended (i.e., with fidelity), positive outcomes for children and/or families can be expected. Positive outcomes should not be expected when evidence-based practices are not implemented with fidelity. Therefore, it is essential for states and local programs to collect, analyze, and use data on the extent to which practitioners are implementing evidence-based practices as intended. Having high quality data on implementation, decision-makers can identify implementation successes and challenges and target valuable resources appropriately. This tip sheet series provides concise guidance for collecting and analyzing high-quality data on the implementation of evidence-based practices. The content was designed for staff of state and local early intervention (Individuals with Disabilities Education Act (IDEA) Part C) and preschool programs for children with disabilities (IDEA Part B 619), but it is relevant for anyone evaluating the implementation of evidence-based practices. The tip sheets address topics that state personnel identified in webinars and workshops the Center for IDEA Early Childhood Data Systems (DaSy) and Early Childhood Technical Assistance Center (ECTA) offered in partnership with the National Center for Systemic Improvement and the IDEA Data Center. The tip sheets are not intended to be comprehensive; readers are encouraged to consult the resources listed in each tip sheet and to obtain support from federally funded technical assistance centers such as DaSy and ECTA, university partners, and others with evaluation expertise.