Client anxiety is often associated with diagnostic testing. In this study, the authors used a grounded theory approach to examine the situational and social factors underlying anxiety associated with HIV testing, analyzing transcripts from semistructured interviews with 39 HIV test recipients in Ontario, Canada (selected based on HIV serostatus, risk experience, geographic region, gender, and number of HIV tests), then integrating emergent themes with existing research literature. Analysis revealed four themes: perceptions of risk and responsibility for health, stigma associated with HIV, the patient-provider power dynamic, and techniques used by test recipients to enhance control in their interactions with providers. Service implications include modifications to information provision during the test session, attention to privacy and anonymity, and sensitivity to patient-provider interactions.