The present paper deals with the typology of informal settlements and zone-wise distribution of slums in the National Capital Territory (NCT) of Delhi. The Economic Survey of Delhi (2002) has identified eight types of settlements with six informal settlements. Since these six types of settlements do not qualify to be classified as formal settlement because of lack of basic amenities, they may also be called as slums in one way or the other. The paper is based on both secondary and primary data. The secondary data were collected from the slum wing of Delhi Municipal Corporation, while the primary data were generated through field survey in South Delhi District for a case study. The study reveals that smaller size of slum clusters is more in number and thus a major chunk of slum population live in them. As far as zonewise distributions of slums are concerned the Central Zone witnessed having the lowest number of slums i.e. 127 constituting 9.95% to the total slums in the Capital Territory as against the South Zone in which maximum number of slums i.e. 389 contributing 30.49% of the total slums in the NCT, Delhi.