This cross sectional study in the Solapur Municipal Corporation (Western Maharashtra) looked at 400 adolescent girls' knowledge on HIV/AIDS. Simple random sampling was used to identify the respondents. Data was gathered through interviews. When compared to a study conducted among adolescents in South Delhi and another among youth in Vadodara district, India (McManus & Dhar, 2008; Kotecha et al. 2011), a larger percentage of girls did not know how HIV is transmitted (54.25% versus 33% and 19.2% respectively). Only 15.75% of girls in this study knew HIV can be transmitted through unsafe sex, versus 74.6% in the Kotecha et al. (2011) study. The percentage of girls who knew that HIV can be transmitted through blood transfusions and from mother to child was also lower in this study than the other two. The study shows that efforts to improve knowledge among adolescent girls, especially those living in slums, should be ramped up, including better information, education and communication strategies targeted at the individual, family, and community levels.