Injury is a common experience for children worldwide. Over 80% of children develop some traumatic stress symptoms in the month following injury. Regardless of injury severity, 15 to 20% of injured children develop persistent and impairing posttraumatic stress symptoms (PTSS), including 5 to 10% who develop posttraumatic stress disorder (PTSD). (Similar rates of symptoms are observed in the parents of injured children.) PTSS are a key predictor of child functional outcomes post-injury. Parents are the most important resource for acutely injured children, and yet are often unaware of how best to help their child. The Internet can provide easily accessible and quick information and tools to a wide range of parents of injured children. This chapter describes the development process for the After the Injury website (www.aftertheinjury.org) from concept to execution, including initial efforts to evaluate the website’s utility and acceptability to parents. After the Injury aims to prevent persistent PTSS and PTSD through a web-based information and psychoeducational intervention. The development of this site highlights several important principles: 1) selecting evidence-informed objectives and content; 2) utilizing user-centered design to guide the site’s look, design, and functionality, and help ensure parent engagement; and 3) incorporating evaluation throughout the process of site development and implementation.