The current study took a multi-informant approach to compare parent to self-report ratings of social vulnerability of adults with Williams syndrome (WS). Participants included 102 pairs of adults with WS and their parents. Parents completed the "Social Vulnerability Questionnaire" and adults with WS completed an adapted version of the questionnaire. Parents consistently reported higher levels of social vulnerability for their son/daughter than the individual with WS reported, with the exception of emotional abuse. The lower ratings of social vulnerability by adults with WS, compared to their parents, offer new information about their insight into their own vulnerability. These findings highlight the importance of teaching self-awareness as a part of a multi-informant approach to interventions designed to target social vulnerability.