More than half of a given population will be exposed to a traumatic event in their lifetime, and, although most individuals will recover on their own, a salient minority will go on to develop posttraumatic stress disorder (PTSD) or other serious threats to wellness and quality of life. Without treatment, PTSD tends to be chronic, and is associated with considerable personal and public health costs. Unfortunately, most individuals with PTSD do not get the care they need because there are a variety of barriers to treatment-seeking (e.g., stigma) and treatment access, including a shortage of well-trained professionals, a scarcity of professionals who provide evidence-based treatment, and the unavailability of expert care outside of city centers. In this chapter, we review the key challenges associated with providing evidence-based treatment to individuals who have experienced trauma, and highlight ways in which Internet-based approaches can be used to overcome these challenges. Next, we describe several existing Internet-based treatment programs for PTSD, and the efficacy of these treatments. Last, we suggest some important considerations for future research that may impact the effectiveness of Internet-based treatments for PTSD.