Background: Healthcare professionals often lack sufficient training to work with stigmatized populations such as persons living with HIV/AIDS (PLWHA) and individuals with substance use disorders (SUD), leading to poorer healthcare and health outcomes. Understanding and addressing stigmas surrounding these groups is crucial to inform the development of competency in student curricula. This study aimed to (1) examine predictors of faculty's inclusion of HIV/AIDS and SUD curriculum and related stigmas, and (2) examine predictors of HIV/AIDS-stigma, SUD-stigma, and knowledge of these stigmas among undergraduate students. Methods: Survey data were collected from undergraduate students (n=1,039) and faculty (n=123) at a Northeastern state university. Multivariable logistic regression examined faculty knowledge, comfort, readiness, and stigma as predictors of curriculum inclusion. Multivariable logistic regression assessed students' perceived inclusion of these topics as predictors of knowledge, controlling for confounding variables. Multivariable linear regression evaluated student knowledge as a predictor of stigma. Results: Faculty readiness was the sole predictor of inclusion of HIV (OR 1.91), HIV-stigma (OR 2.84), SUD (OR 2.90), and SUD-stigma (OR 4.62) in curricula. Students' perceived inclusion of HIV-stigma and SUD-stigma predicted knowledge of these stigmas (OR 2.26 and OR 1.69, respectively). Student knowledge of HIV-stigma and SUD-stigma predicted higher perceived public stigma ([beta]=0.20 and [beta]=0.38, respectively). Conclusions: Integrating anti-stigma curriculum regarding PLWHA and individuals with SUD is crucial for decreasing stigma and building cultural competence in healthcare students. Faculty development programs targeting readiness to include stigma-related content would increase student knowledge and reduce stigmatizing attitudes. Targeted interventions enhancing faculty readiness and undergraduate stigma education are recommended to improve healthcare competency with these populations. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]