AbstractBeckwith–Wiedemann syndrome (BWS) is an overgrowth and epigenetic disorder caused by changes on chromosome 11p15. The primary features requiring management in childhood include macroglossia, omphalocele, lateralized overgrowth, hyperinsulinism, and embryonal tumors. Management guidelines have not been developed for adults with BWS and there have been few studies to assess the clinical needs of these patients. Furthermore, there have been few studies on the psychosocial implications of BWS in children or adults. Here, we present a descriptive summary of data gathered from two separate adult BWS cohorts. The first, a patient‐based survey cohort, includes self‐reported health information and recollections about BWS experiences, while the second provides results of a medical record‐based assessment from patients in an overgrowth registry. Results highlight the clinical features and medical issues affecting two large independent cohorts of adults with BWS while noting similarities. Open‐ended questions asked of the survey cohort yielded themes to guide future qualitative studies. Finally, the study demonstrated the reliability of patient‐reported data and the utility of international partnerships in this context.