Objectives. To describe HIV testing among clients in the Targeted Highly Effective Interventions to Reverse the HIV Epidemic (THRIVE) demonstration project and evaluate testing frequency. Methods. We identified factors associated with an average testing frequency of 180 days or less compared with more than 180 days using adjusted Poisson regression models. We performed the Kaplan-Meier survival analysis to compare time to diagnosis by testing frequency. Results. Among 5710 clients with 2 or more tests and no preexposure prophylaxis (PrEP) prescription, 42.4% were tested frequently. Black/African American clients were 21% less likely and Hispanic/Latino clients were 18% less likely to be tested frequently than were White clients. Among 71 Black/African American and Hispanic/Latino cisgender men who have sex with men and transgender women with HIV diagnoses, those with frequent testing had a median time to diagnosis of 137 days, with a diagnostic testing yield of 1.5% compared with those tested less frequently, with 559 days and 0.8% yield. Conclusions. HIV testing at least every 6 months resulted in earlier HIV diagnosis and was efficient. Persons in communities with high rates of HIV who are not on PrEP can benefit from frequent testing, and collaborative community approaches may help reduce disparities. (Am J Public Health. 2023;113(9):1019-1027. https://doi.org/10.2105/AJPH.2023.307341).