Understanding the lives of adolescents and young adults (UDAYA) in Bihar and Uttar Pradesh is designed to establish the levels, patterns and trends in the situation of younger (10–14) and older (15–19) adolescents and to assess the factors that influence the quality of transitions they make. The corresponding datasets contain information on adolescents aged 10-19 and the households to which they belonged. Five categories of adolescents were included in the sample: unmarried adolescent girls and boys aged 10–14 and 15–19 and married girls aged 15–19. Data disaggregated by these categories are representative at the state level. The survey was conducted in Uttar Pradesh (September 2015 to January 2016) and Bihar (January 2016 to July 2016).