A measure of graduate student sense of belonging with adequate psychometric properties was established. We conducted secondary analysis using data from the 2021 Graduate Student Experiences at Research Universities Survey and found evidence supporting the underlying factor structure of sense of belonging as a single latent trait among 12 rating scale items. Furthermore, there was weak to strong evidence that sense of belonging was associated with internal and external factors such as mental distress and graduate program satisfaction. From these results, we expanded on graduate students’ sense of belonging and provided evidence to inform decisions that researchers, administrators, and practitioners can make with respect to graduate education and student success.