Background: Social community may play a role in how successful undergraduate engineering mentoring programs are in increasing diversity, retention rates, and graduation rates. However, there is minimal research about how mentoring programs influence the development of the social community outcomes of connectedness, satisfaction, social capital, resilience, and communities of practice, or whether these outcomes differ among demographic groups. Purpose: This work examines the social community outcomes of undergraduate engineering mentoring program participants and makes recommendations for programs based on participant experiences and outcomes. Methods: In this exploratory multi-methods study, we use quantitative and qualitative methods to examine social community among participants in a mentoring program for undergraduate engineering students. More specifically, we administered a survey and conducted interviews to examine the five social community outcomes among engineering undergraduate participants in the University of Michigan's Michigan Science, Technology, Engineering, and Mathematics (M-STEM) Academies. Survey results were evaluated for social community outcomes among demographic groups and a thematic analysis was performed on the interview responses. Results: Our findings indicate that: (1) female participants value their M-STEM connections differently from male participants; (2) program alumni engagement has a positive impact on current participants' social community outcomes; and (3) strategies for resilience vary based on sex and race. Conclusions: We recommend that mentoring programs offer face-to-face activities to help female participants develop stronger connections with other participants. Programs should also offer ways for program alumni to remain engaged with the program and continue to support younger mentoring program cohorts.