Background: Our previous study to understand end-of-life care of adolescents and young adults (AYAs) had a suboptimal survey response rate by bereaved caregivers. Objective: To identify sociodemographic factors associated with caregiver nonparticipation. Design/Setting/Subjects: Post hoc analysis of a retrospective multicenter cohort study of caregivers of deceased AYAs from 2013 to 2016. Measurements: Exposures: race, ethnicity, area-, and household-poverty. Primary outcome: survey participation. Secondary outcomes: loss to follow-up at each recruitment step. Results: Thirty-five of 263 eligible caregivers participated in the survey (13.3%). Caregivers of AYAs living in high-poverty zip codes were significantly more likely to have a disconnected or incorrect phone number (odds ratio [OR] 2.12; 95% confidence interval [CI] 1.04-4.58; p = 0.03). Caregivers of nonwhite AYAs were significantly less likely to participate (OR 0.35; 95% CI 0.12-0.87; p = 0.01). Conclusions: Caregivers of patients living in poverty are less likely to be reached by traditional recruitment efforts. Caregivers of racial/ethnic minority patients are less likely to participate overall.