This paper reports on a summative analysis of Exploratory Reading Groups (ERGs), a low time-commitment, relational, student-led reading group program designed to provide students from any background and year with a broad exploration of computing research. Since prior work, the program was institutionalized as a 1-credit course with a greater emphasis on strengthening pipelines into research labs. In analyzing 3 quarters of data from 136 participants, we found diverse indicators of impact. Surprisingly, despite the lightweight nature of the program (${\sim}2$ hours/week), we observed a statistically significant increase in satisfaction with their intellectual development at the university; confidence in reading, presenting, and communicating about their field; sense of belonging for women and minoritized ethnic groups; alignment with faculty goals in joining research labs (greater desire to make a research contribution and publish, decreased desire to join for the purpose of exploration); and engagement in the `reconsideration’ dimension of career identity formation. Over 75% of the participants continued on into group research projects for undergraduate students. The effectiveness of this scalable, lightweight initiative shows the promise of ERGs as a tool to support students in computing and points to future research directions on designing other lightweight, relational, scalable learning experiences.