The Communication Play Protocol (CPP) is a semi-naturalistic, lab-based observational procedure that showcases parent-child interactions. This article reflects on how the CPP has matured since we described it over 25 years ago in the May 1999 issue of Perspectives. We emphasize how the CPP has provided us with a stable frame to observe both typically developing children and children with developmental challenges including autism spectrum disorder as they communicate with caregivers in a range of contexts. We also describe three versions of the CPP that have been designed to address different research questions and several methods including engagement state coding and rating items that have been used to extract data from video records of the CPP. We conclude that the CPP can provide both researchers and clinicians with a valuable way to systematically capture variations in language development.