After pediatric injury, transient traumatic stress reactions are common, and about 1 in 6 children and their parents develop persistent posttraumatic stress (PTS) symptoms that are linked to poorer physical and functional recovery. Meta-analytic studies identify risk factors for persistent PTS, including preinjury psychological problems, peritrauma fear and perceived life threat, and posttrauma factors such as low social support, maladaptive coping strategies, and parent PTS symptoms. There is growing prospective data indicating that children's subjective appraisals of the injury and its aftermath influence PTS development. Secondary prevention of injury-related PTS often involves parents and focuses on promoting adaptive child appraisals and coping strategies. Web-based psychoeducation and targeted brief early intervention for injured children and their parents have shown a modest effect, but additional research is needed to refine preventive approaches. There is a strong evidence base for effective psychological treatment of severe and persistent PTS via trauma-focused cognitive behavioral therapy; evidence is lacking for psychopharmacological treatment. Pediatric clinicians play a key role in preventing injury-related PTS by providing "trauma-informed" pediatric care (ie, recognizing preexisting trauma, addressing acute traumatic stress reactions associated with the injury event, minimizing potentially traumatic aspects of treatment, and identifying children who need additional monitoring or referral).