This guide for district and school leaders shows how to recognize opportunities to embed randomized controlled trials (RCTs) into planned policies or programs. Opportunistic RCTs can generate strong evidence for informing education decisions--with minimal added cost and disruption. The guide also outlines the key steps to conduct RCTs and responds to common questions and concerns about RCTs. Readers will find a real life example of how one district took advantage of an opportunity to learn whether a summer reading program worked.