Objective The Interpersonal Theory of Suicide (ITS) implicates thwarted belongingness and perceived burdensomeness as casually related to suicide desire. The self-report Interpersonal Needs Questionnaire (INQ) is the most commonly used measure to assess belongingness and burdensomeness, including in youth. No parent-report version of the INQ exists. The current study adapted the ten-item version of the INQ (INQ-10) for parent report of youth belongingness and burdensomeness, thereby moving ITS research in youth to a multi-informant measurement approach, and examined its factor structure and convergent and concurrent validity. Methods Participants were 168 clinic-referred youths ages 9–17 years (58.9% female; Mage = 11.91) and their parents. Results Findings supported a two-factor structure of the parent INQ. In support of convergent and concurrent validity, parent-reported belongingness and burdensomeness were significantly associated with youth-reported belongingness and burdensomeness, suicide ideation, anxiety symptoms, depressive symptoms, and impairment. Conclusions The current study provides initial support the INQ-parent version as a valid measure to complement youth self-reports of belongingness and burdensomeness.