Research Experience for Teachers (RET) programs have been placing K-12 teachers in university research labs for almost three decades (Pop et al., 2010). However, the long-term impacts are rarely explored. This paper summarizes data from a survey study of 135/158 teachers (88% response rate) who participated in Stanford University's RET programs between 2005 and 2017. The purpose of the study was to gauge the lasting impact of RET, if any, on teacher retention and classroom and professional practices. The data strongly suggest that participants gain long-lasting personal and professional benefits from participation - value that seems to be especially magnified for mid- to late-career teachers who are well established in their teaching practices but committed to continuous improvement. Furthermore, if the self-reports are accurate, these results would presumably also accrue to teachers' students. Findings are attributed to the efficacy of the RET model. The authors argue for a nationwide evaluation of the efficacy of RET for teacher retention and professional development.