High-quality preschool programs are heralded as an effective policy tool to promote the development and life-long wellbeing of children from low-income families. Yet evaluations of recent preschool programs produce puzzling findings, including negative impacts, and divergent, weaker results than were shown in demonstration programs implemented in…

Background: Educational interventions are often complex, and their outcomes could be due to factors not focused on in the impact evaluation. Therefore, educational evaluations using a randomised control trial (RCT) design approach need to go beyond obtaining the impact results alone. Purpose: Process evaluation is embedded in the evaluation design…