Introduction: Menstrual Hygiene Management (MHM) involves using clean absorbents, maintaining body hygiene, and practicing safe disposal methods. This study aimed to compare the knowledge and MHM practices of adolescent school girls from an urban and a slum area in Delhi. Methods: The study included 85 and 168 girls aged 13-18 years from an urban and a slum area school of Delhi respectively. Information was gathered using a pre-designed, pre-tested and structured questionnaire with 12 questions related to the knowledge about menstruation and MHM practices. Results: 92.9% of urban and 85.7% of slum area school girls knew menstruation as a physiological process whereas 3.5% of urban school girls were unaware of the cause of menstruation compared to13.7% of the slum area school girls(p=0.01). All girls identified sanitary pads as their ideal absorbent, and 100% of the participants used them. Satisfactory cleaning practices were 31.8% in urban area verses 4.8% in slum area school girls. (p = 0.0001). 95.3% of urban and 92.8% of slum area school girls were disposing pads in routine waste. Conclusion: The study found significant differences in menstrual knowledge and MHM practices between urban and slum area school girls, with urban girls reporting comparatively better knowledge as well as MHM practices. Both the group of girls reported 100% usage of sanitary pads, but improper disposal practices need attention. Proper disposal facilities in schools are recommended to prevent environmental pollution.