Runaway and homeless youth face multiple challenges to their health and experience inadequate access to health care services. This article describes a Web-based Personal Health Information System (PHIS) called Healthshack that was specifically designed to improve health care access and health outcomes for runaway and homeless youth at a community-based agency that served homeless youth and young adults up to age 24. The program was developed in partnership with homeless youth and piloted by public health nurses. Preliminary findings from the program indicate that a PHIS is acceptable to runaway and homeless youth and feasible to incorporate into the flow of a youth agency. Thus, a PHIS may be an innovative model of service delivery for other marginalized populations.