In this chapter, we explore the variation within the increasingly-threatened species of the Trachypithecus genus living in the Indo-Burmese region. These species live in habitats varying from shrubby karst to closed-canopy habitat with most in fragmented/disturbed primary or secondary forests that experience wet and dry seasons in a tropical monsoon climate. Trachypithecus species have adaptations for their highly-leafy, yet selective, diets, including high rates of inactivity and feeding that may shift seasonally, with habitat quality or by age-sex class. Home ranges are used differently depending on season, habitat quality and behaviour and there is variable territoriality. Predation pressure appears to be minimal, with the exception of human poachers. Most groups are unimale reproductive groups, although larger multimale and smaller all-male groups also exist. It is unclear whether these species exhibit female philopatry and/or dual dispersal and many soeices lack a strict/overt dominance hierarchy. Maturing around 3-5 years of age, these species have relaxed seasonality to mating/birth patterns and intervals are roughly two years with weaning at 18-21 months. Within this group research has primarily been concentrated on the distribution and habitat, diet and population status of limestone langurs. Conservation efforts should focus on impacts of deforestation and fragmentation.