This book introduces Ulti, a secret language spoken by the Hijra-Koti community in West Bengal, from a sociolinguistic and formal linguistic perspective. It explores the sociopolitical conditions in which Ulti came into being, its purposes and significance for the speech community, and how it is used within the multilingual ecology of Bengal. This book also presents an analysis of the lexicon of Ulti, which is unique in its specificity to the lifestyle and social structure of the Hijra-Koti community, and a grammatical analysis of Ulti as a mixed language which is embedded in, yet distinct from, the grammatical framework of Bangla.