Using a national database of patient safety incident reports in the United Kingdom, this study characterized primary care-related incidents among vulnerable children and used thematic analysis to identify priority areas for systems improvement. Over 1,100 incident reports were identified; nearly half resulted in some degree of harm but most (39%) were considered ‘low harm.’ Children with  protection-related vulnerabilities experienced harm from unsafe care more frequently than children with social-, psychological, or physical vulnerabilities. The authors identified system priority action areas to mitigate harm among vulnerable children, including improving provider access to accurate information and reducing delays in provider referrals.