This study is twofold and examined the relationship of cognitive processes including various types of rumination and world assumptions to posttraumatic growth (PTG) as well as other indicators of psychological functioning. Secondly, we examined the relationship of these cognitive processes and PTG to a number of physical health measures including immune functioning and health related quality of life (HRQL). We also examined PTG in relation to behaviors including high-risk behaviors and antiretroviral therapy adherence. Participants included a convenience sample of 118 HIV-positive adults who were receiving medical treatment at an urban HIV clinic. Posttraumatic growth was measured with the Posttraumatic Growth Inventory (PTGI; Tedeschi & Calhoun, 1996). Cognitive processes were assessed with the Rumination Scale (RS; Calhoun, Cann, Tedeschi, & McMillan, 2000) and the World Assumptions Scale (WAS; Janoff-Bulman, 1989). Psychological Distress was assessed with the Impact of Event Scale (IES; Horowitz, Wilner, & Alvarez, 1979), Psychiatric Symptom Index (PSI; Ilfeld, 1976), and the Beck Depression Inventory-Fast Screen for Medical Patients (BDI-FS; Beck, Steer, & Brown, 2000). Adherence was measured with the AIDS Clinical Trial Group Follow-up Questionnaire (ACTG; Chesney et al., 2000). Health related quality of life was assessed with the Medical Outcomes Study 36-item Short Form (SF-36; Ware, Kosinski, & Keller, 1994). Results indicate that the type and timing of ruminations are important in understanding their relationship to PTG and distress whereas positively biased world assumptions are related to higher levels of PTG. Additionally, although PTG was not related to health status or HRQL, it was negatively related to risk behaviors.