OBJECTIVE: Eating disorder (ED) symptoms have been studied in adults with other rare genetic conditions but not in Williams syndrome (WS). This study examined the prevalence of ED symptoms in adults with WS and associated clinical and demographic factors. We hypothesized that a proportion would screen positive for an ED, primarily with avoidant/restrictive food intake disorder (ARFID) or binge-eating presentations. METHOD: Adults with WS completed modified versions of the Eating Disorder Assessment for DSM-5 and the Pica, ARFID, and Rumination Disorder Questionnaire, administered as semi-structured interviews by trained research staff. Participants also completed a medical history questionnaire. We used descriptive and between-group analyses to examine clinical and demographic characteristics of ED-positive and ED-negative groups. RESULTS: Of the 86 participants, more than one quarter (n = 24, 28%; 95% CI [20%, 38%]) screened positive for an ED. Adults who screened positive for an ED most commonly had binge-type EDs (n = 15, 63%; 95% CI [43%, 79%]) and ARFID-type EDs (n = 7, 29%; 95% CI [15%, 49%]). Of those who screened positive, 96% reported they had never been previously diagnosed with an ED. DISCUSSION: Our study provides initial evidence of a high frequency of positive ED screens in adults with WS, most commonly ARFID-type and binge-type EDs. Our findings also suggest that, while prevalent in WS, EDs typically go undetected, and that it may be difficult to identify at-risk individuals. There is a need to validate ED screeners for adults with WS to enhance detection and access to care.