Context: HIV testing is a critically important first step in preventing and reducing HIV transmission. Community-based organizations (CBOs) are uniquely positioned to provide HIV testing and other prevention services to populations disproportionately affected by HIV infection. Objective: The purpose of this analysis was to assess CDC-funded health department (HD) and CBO testing programs during 2012-2017, including the number of tests and HIV positivity. Design: This is an analysis of National HIV Prevention Program Monitoring and Evaluation HIV testing data submitted between 2012 and 2017 to CDC. Setting: Sixty-one CDC-funded state and local HDs in the United States, Puerto Rico, and the US Virgin Islands and between 122 and 175 CDC-funded CBOs, depending on the year. Participants: Persons who received HIV testing at CDC-funded CBOs and HDs.Main Outcome Measure: The number of HIV tests and positivity at CBOs were compared with HDs overall and to HDs in non-health care settings that, like CBOs, include HIV risk data and are in similar locations. Results: CBOs accounted for 7625 (8%) new diagnoses but conducted only 3% of the almost 19 million CDC-funded HIV tests from 2012 to 2017. Newly diagnosed HIV positivity at CBOs (1.4%) was nearly 3 times the new positivity at HDs overall (0.5%) and twice that of new positivity at HDs in non-health care settings (0.7%). A higher proportion of tests at CBOs were conducted among groups at risk, and new HIV positivity was higher for most demographic and population groups than new HIV positivity at HDs in non-health care settings. Conclusion: These findings demonstrate the essential role CDC-funded CBOs have in reaching, testing, and diagnosing groups at high risk for acquiring HIV infection.