Social reintegration is an important part of young adult cancer patients' transition to survivorship care. As part of a mixed methods study exploring the social functioning of young adult cancer patients during this transition process, participants (N = 13) completed four selected measures from the Patient-Reported Outcomes Measurement Information System (PROMIS) social and mental health domains within ∼6 months of completion of active treatment and 3 months later. The majority of participants (n = 10) had T-scores within normal limits on all measures. Three participants had T-scores in the mild or moderate impairment range across time points. No significant differences were found between groups at Time 1 and Time 2 on any of the four measures.