Background: Though guidelines recommend lifelong follow-up for pediatric and adolescent/young adult (AYA) cancer survivors, this has been challenging to implement in clinical practice. We constructed an institutional cohort of pediatric/AYA cancer survivors in order to evaluate follow-up patterns and identify predictors of cancer center-based follow-up. We hypothesized that follow-up would be lower for patients with greater individual- and area-level socioeconomic disadvantage and longer time since treatment. Methods: This retrospective cohort study used EHR data at an academic medical center. We included all patients who completed cancer treatment between 2010-2019 and were aged 0-29 years at last treatment date. Treatment was defined by diagnosis/procedure codes and medication records for chemotherapy, radiation, stem cell transplant, and cancer surgery. The primary outcome of cancer center-based follow-up was defined by clinic visits in an oncology department through 12/31/2022. Patients who died were excluded after the date of death. Multivariate logistic regression models (overall, age 0-19, age 20-29) evaluated the association of follow-up with age, sex, race/ethnicity, treatment intensity, insurance type, primary language, distance to cancer center, and area deprivation index (ADI, a composite measure of socioeconomic disadvantage). Results: 2210 patients were included with an overall rate of cancer center-based follow-up that decreased from 94% 1 year after treatment to 61% at 2-3 years, 45% at 4-5 years, and 35% at 6-7 years. Follow-up was not significantly associated with race/ethnicity, insurance type, primary language, or ADI for overall or age-specific cohorts. Patients >100 miles away had lower odds of follow-up. Increasing age was associated with decreased odds of follow-up, and this trend persisted over time since treatment (Table). Conclusions: Patterns of decreased pediatric/AYA cancer survivor follow-up were largely predicted by age and time since treatment. Further work is ongoing to understand drivers of follow-up disparities, including transfers of care and insurance type among AYA patients and the role of community support and telemedicine in healthcare access and health promotion.