Supporting upward transfer students is critical to diversifying STEM. This study provides insight into how we can best support upward transfer students in computing, one of the least diverse STEM disciplines. Specifically, we expand upon recent research on sense of belonging to examine how the predictors of belonging might be unique for upward transfer students, focusing closely on upward transfer women's experiences. Findings highlight three unique predictors of sense of belonging for upward transfer students beyond those documented in prior research on students in the aggregate. Other college experiences -- like feeling supported by computing peers -- positively predicted belonging for all students, but were not equitably available to upward transfer students, with upward transfer women reporting the lowest levels of peer support compared to all other groups.