The SUMMIT-P project is a multi-institutional endeavor to leverage interdisciplinary collaboration in order to improve the teaching of undergraduate mathematics courses in the first two years of college. One goal of this work is to establish collaborative communities among the institutions involved. As part of the project, institutions visit one another on site visits that are structured according to a common protocol. The site visits have been valuable to the project. Participating institutions report the exchange of actionable ideas and feedback; members of the grant leadership team have used the site visits to direct the overall project, and evaluators have refined questions and identified trends that will help their assessment of the project. At a deeper level, the site visits have created a strong sense of community among those involved in every aspect of the SUMMIT-P project.