Objective: To describe how young adult cancer caregivers (YACC) use social media for social support during a cancer experience. Methods: Eligible YACC were 18 to 39 years, used Facebook and/or Instagram at least once per week, and cared for an adult cancer patient diagnosed 6 months to 5 years prior (N = 34). Recruitment of a cross-sectional sample occurred through oncology clinics in Utah and online advertising by caregiving and cancer organizations from September 2017 to June 2018. Semi-structured telephone interviews were recorded, transcribed, iteratively coded, and qualitatively analyzed, yielding four categories concerning how YACC use social media. Results: Caregivers were most commonly spouses aged 29 years on average (range 21-38); cancer patients were 37 years (range 19-76). Analysis yielded four distinct yet related categories: Category 1: Posting about cancer on social media often begins as a strategy for YACC to efficiently provide updates about the cancer patient. Category 2: Caregivers who actively post on social media experience a variety of different functional social supports to which they otherwise would not have access. Category 3: Posting about cancer online presents an opportunity for negative consequences. Category 4: Potential for negative consequences influences how some caregivers use social media. Conclusions: Supportive services, including social media-based supports, are needed for YACC in formats that are convenient for them as they balance their caretaking duties with their daily lives.