Since its inception in 2003, the IWCA Summer Institute (SI) has been understood within the writing center field to be an important professional development opportunity for new and experienced writing center professionals (WCPs). Publications on the SI to date have focused on anecdotal perceptions of the benefits to leaders and participants or on a single outcome, such as research output. Thus, the writing center field knows little about how and in what ways participants perceive the SI's benefits across cohorts and across a variety of professional areas. By gathering quantitative and qualitative data from every SI cohort from 2003 to 2019, the goal of this study was to identify and define the benefits of the SI, focusing in particular on how participants themselves understand them. The survey received 161 responses, a response rate of approximately 27%; all 17 years of the SI were represented. The study found that, despite the field's shifting priorities since 2003, the concerns and needs of WCPs have remained relatively constant over time, and that the SI serves the most pressing administrative needs of participants.