HIV partner services (HIV PS) is an effective strategy for diagnosing HIV infection. Sex/needle-sharing partners of individuals diagnosed with HIV are notified about potential exposure and offered HIV testing and other services. We assessed the HIV PS contribution to HIV diagnoses in the United States and assessed priority areas for improvements. National HIV Monitoring and Evaluation Partner Services and case surveillance data reported to the Centers for Disease Control and Prevention for 2019 were used for this analysis. The percentage of all new diagnoses that HIV PS programs reported is described nationally and by state. Linkage to HIV medical care among newly diagnosed partners is described. Potential increases in diagnosing HIV infection are assessed by HIV PS step to identify priority areas for improvement. HIV PS contributed 1214 of 35,164 (3.5%) of all diagnoses nationally in 2019, and contributions ranged from 0% to 31.8% by state. Of partners tested with nonmissing data, 22.7% were newly diagnosed. An estimated 1692 new partner diagnoses were lost during HIV PS steps. Steps resulting in the highest losses included index patients not being interviewed, partners not being tested for HIV, and index patients not being located. Seventy-two percent of partners newly diagnosed with HIV were linked to HIV medical care. HIV PS is an effective strategy for diagnosing HIV, and a high percent of sex/needle-sharing partners was newly diagnosed with HIV. Expanded HIV PS in some states and targeted improvements in HIV PS steps can enhance the contribution of HIV PS toward achieving national goals.