Voluntary Counseling and Testing (VCT) is an HIV prevention strategy that promotes the principles of confidentiality and informed consent. International research has highlighted VCT counselors' isolation from service planning and the contradictions they negotiate between local values and global testing recommendations. In Brazil, studies have identified many limitations, including counselors' difficulties to implement a vulnerability approach to HIV prevention as recommended in the country's national guidelines. These studies, however, have not considered the particularities of the institutional contexts where counselors work. This research addresses these gaps in the VCT literature by exploring how VCT services are organized and how counselors perceive and perform their practices in the state of Rio de Janeiro, Brazil.