Although considerable research has evaluated HIV/AIDS complacency and inadequate HIV testing practices as important causes for the growing HIV epidemic among men who have sex with men (MSM), many unanswered questions remain. Among these, three are particularly important: (1) does HIV/AIDS complacency due to beliefs about highly active antiretroviral therapy (HAART) cause or is caused by heightened HIV-acquisition behavior; (2) do differential influences of HAART-efficacy beliefs explain, in part, racial HIV-infection disparities; and (3) do main reasons for not testing for HIV, testing intentions, and potential use of an over-the-counter rapid HIV test vary by important demographic and risk groups among MSM who have never tested for HIV? To help address these questions, this dissertation evaluated data from two cross-sectional surveys of MSM from eight U.S. cities recruited at MSM-identified venues (1998-2000) and internet websites (2007). Findings from these surveys suggest that among MSM: (1) HIV/AIDS complacency, shaped in part by strong beliefs that HAART mitigates HIV/AIDS severity and HIV susceptibility, both causes and is caused by heightened HIV-acquisition behavior; (2) racial HIV- infection disparities are explained, in part, by racial/ethnic differences in the strength of these HAART-efficacy beliefs and their influence on HIV-infection risk; (3) most who have never tested for HIV (NTMSM) report not testing because of low perceived risk, structural barriers, and fear of testing positive, and although many report substantial risk behavior, few have strong testing intentions; and (4) main reasons for not testing vary by age, racial/ethnic, and risk subgroups, however, most NTMSM within these subgroups are accessible to prevention services and strongly intend to use an over-the-counter rapid HIV test should it become available.Given the dramatic improvement in HAART to prolong quality life, compelling evidence that HAART reduces HIV transmission, and the growing HIV epidemic among MSM attributed, in part, to inadequate testing, translating these findings into contemporary prevention practices may be of considerable importance to reducing HIV incidence among MSM. This dissertation hopes to spur new research needed to replicate these findings and to inform the development of effective interventions to reduce HIV-acquisition risks, racial disparities, and undiagnosed HIV infection among MSM.