Substance use disorders are common among people living with HIV (PLWHA), and PLWHA with untreated substance use are less likely to receive antiretroviral therapy (ART) or achieve viral suppression when ART is prescribed. Integrated behavioral and medical interventions are one approach used to treat complex chronic illnesses, including HIV and substance abuse (SA). As the potential benefit for integrated HIV-substance abuse treatment is recognized, the number of providers attempting to integrate care is growing. Integrated care models can range from coordinated to colocated to fully integrated models. Providers need a better understanding of these implementation options for HIV-substance abuse treatment and how they impact providers of different disciplines. Between April and November 2006, interviews exploring the process of implementing an integrated HIV-substance abuse intervention were completed with clinic staff at three diverse HIV clinics in North Carolina. Key differences in implementation between sites were found. The degree of integrated care between sites ranged from colocated to integrated, and clinic staff perceived each integrated model to have advantages and disadvantages. Recommendations for implementing HIV-SA integrated care are made.