This paper presents the challenges and lessons learned from an external evaluation of a regional program designed to improve science and literacy achievement for high-needs students in grades Kâ6. The program's goals were to strengthen teacher understanding of science and quality of instruction in 4 districts, through professional development and coaching that supports inquiry-based science kit instruction. Lessons learned for evaluators include the importance of communication with project researchers to understand the day-to-day implementation issues that could potentially bias analytic findings, the challenges around access to student-level data to create propensity-score matched samples when random assignment is not possible, the use of descriptive data and graphical representations to improve clarity of the findings to local stakeholders, and documenting implementation issues throughout the study to guide researchers in improving implementation in future years.#ScienceAchievement #InquiryScience #ScienceKit #Prek-12EducationalEvaluation #ScienceInstruction #ProfessionalDevelopmentinScience #2011Conference