Approximately half of all new HIV infections in the US arise from persons who are aware of their HIV- positive status. In some cases, these individuals have informed their partners of their positive serostatus and their partners have consented to sex assuming the risk of infection. In other cases, the partners have not been informed. The majority of US states have passed HIV-specific laws that make it a crime for PLH to engage in sexual activities with a partner without having first disclosed his or her HIV-positive status. Our research suggests that the criminalization of HIV exposure is not an effective HIV prevention intervention. There are also lingering concerns about the potential deleterious effects of the criminalization of HIV exposure (e.g., increasing stigma, reinforcing HIV-related discrimination, deterring testing). The National HIV/AIDS Strategy recommends that to minimize the potential negative effects of criminalizing HIV exposure and to maximize national efforts to prevent the spread of HIV, we must ensure that HIV exposure laws support our current understanding of best public health practices for preventing [transmission of] HIV. Yet to our knowledge, no studies have examined the actual intervention efforts developed for these individuals by the agencies that work with them the most-state and local health departments. The proposed study will, we believe, be the first in the US to explore how US health departments identify, verify, and intervene with PLH who are, or are believed to be, engaging in behaviors that risk forward HIV transmission with partners to whom they have not disclosed their HIV-positive status. The study will identify the variety of interventions used in health departments to respond to this client group and will evaluate the effectiveness of one state health department's program to assist PLH who put others at risk of infection. The latter will be accomplished through a preliminary quantitative analysis, using client case records and integrated HIV/STI surveillance data, of the effectiveness of the Colorado Department of Public Health and Environment's intervention efforts with this client group.