Objective: Every year, 500,000 youths in the U.S. with chronic disease turn 18 years of age and eventually require transfer to adult subspecialty care. Evidence-based interventions on the organization of transfer of care are limited, although engagement and retention in adult clinic are considered appropriate outcomes. Sustained continuity of care improves patient satisfaction and reduces hospitalization. Methods: We conducted a prospective, nonrandomized cohort study of patients with pediatric endocrine conditions, age 16 to 26 years, enrolled upon referral to the adult endocrine clinic of a physician trained in both adult and pediatric endocrinology (Med+Peds endocrinologist). Patients differed based on whether their referral originated from another pediatric endocrinologist (traditional transfer) or if the Med+Peds endocrinologist previously saw the patient in his pediatric endocrine clinic (guided transfer). Rather than relying on arbitrary age criteria, guided transfer to adult clinic occurred when physician and patient considered it appropriate. The primary outcome was show rate at the first and second adult visits. Results: Of 36 patients, 21 were referred by another pediatric endocrinologist and 15 underwent guided transfer. For traditional transfer, show rate to the first and second visit was 38%, compared to 100% in the guided transfer group (P = .0001). Subgroup analysis of 27 patients with diabetes revealed that both groups had similar initial hemoglobin A1c (P = .38), and the guided transfer group maintained hemoglobin A1c. Conclusion: Most traditional transfers were unsuccessful. Guided transfer was significantly more effective, with every patient successfully transferring, and could be implemented with adult endocrinologists willing to see patients in the pediatric clinic. Abbreviations: DKA = diabetic ketoacidosis; HbA1c = hemoglobin A1c; Med+Peds = Internal Medicine and Pediatrics.