- Purpose: Despite the risk for late effects in adult survivors of cancer in childhood or adolescence, many survivors fail to transition from pediatric to adult long-term follow-up (LTFU) care. The purpose of this study was to identify the barriers and facilitators of transition from pediatric to adult LTFU care. Methods: In this qualitative study, 38 Canadian survivors of cancer in childhood or adolescence, currently aged 15-26 years, were interviewed using semi-structured, open-ended questions. Participants belonged to one of four groups: pre-transition (n=10), successful transition (n=11), failed to transition (n=7), and transitioned to an adult center but then dropped out of adult care (n=10). A constructivist grounded theory approach was used to analyze the interview data. This approach consisted of coding transcripts line by line to develop categories and using constant comparison to examine relationships within and across codes and categories. Interviewing continued until saturation was reached. Results: Three interrelated themes were identified that affected the transition process: micro-level patient factors (e.g., due diligence, anxiety), meso-level support factors (e.g., family, friends), and macro-level system factors (e.g., appointments, communication, healthcare providers). Factors could act as facilitators to transition (e.g., family support), barriers to transition (e.g., difficulty booking appointments), or as both a barrier and a facilitator (e.g., anxiety). Conclusion: This study illustrates the interaction between multiple factors that facilitate and/or prevent transition from pediatric to adult LTFU cancer care. A number of recommendations are presented to address potential macro-level system barriers to successful transition.