This convergent mixed method quasi-experiment study evaluates the effectiveness of an HIV Prevention Webcourses on reaching HIV related competencies among college students at a large public university in Florida. College students in health majors participated in the study, experiment group were students enrolled in the HIV Webcourses and comparison group were students who enrolled in non-HIV related courses from the same college. Six HIV competencies along with HIV knowledge were measured. Qualitative comments on own learning were also gathered from the experiment group of students. A total of 944 students participated (508 experimental and 436 comparison students). The reliability of the 6-item HIV competency scale showed satisfactory internal consistencies (Cronbach alpha = 0.914; CITCs ranged 0.670-0.804). Regression analyses, controlling for their baseline scores, showed that students in the HIV Webcourses scored significantly higher than comparison group (all p<0.001) on all the six competencies. Regression analyses also showed significant differences on objective HIV knowledge test, perceived HIV knowledge in general and about HIV testing specifically between groups (p<0.001). Students commented they genuinely loved this course as it was extremely well organized, very useful, interesting and informative, and enjoyed the professor's passion of the topics. Students also commented how the personal stories and videos gave perspectives and provided life-changing lessons. Both the quantitative and qualitative data on student learnings convergently demonstrated the impact of this online course. Current study suggested effective design strategies and provided data to support the effectiveness of Webcourses on reaching course-related competencies among college students.