This paper examines mapping and related data-gathering at geographical locations of vulnerable urban groups with regard to risky sexual behaviors and alcohol/drug use in the capital city of Delhi. The aim is to describe the situations of special geographic locations and sub-groups in relation to alcohol/drug use and risks of HIV/STI infections. The study was part of a community program for alcohol and drug users in slum communities in West and East Delhi carried out by the National Drug Dependence Treatment Centre (NDDTC) of the All India Institute of Medical Science (AIIMS), New Delhi, India. As part of a WHO multi-centered qualitative study among selected groups, mapping was done at different sites concerning alcohol use, social contexts, involvement in sexual risk behavior, availability of sex partners and related factors. Easy access to alcohol and drugs, accompanied by availability of sex workers appeared as compound risk factors in the study sites. Reported risky sexual behaviors included nonuse or irregular use of condoms, multiple sex partners, group sex, and anal sex with hijras (eunuchs).