LASI-DAD is an in-depth study of late-life cognition and dementia. It draws a sub-sample of 4,000+ LASI respondents aged 60 and older and administers in-depth cognitive tests and informant interviews. LASI is an ongoing cohort study of 72,000 community-residing older adults aged 45 and older and their spouses regardless of age, with an oversample of persons aged 65 and above.The study design involves following all individuals who move into institutions, although that number is expected to be very small in India. Using the Census as the sampling frame, LASI is representative of both the nation as a whole and each state and union territory. Due to administrative and linguistic considerations, the fieldwork for the main LASI unfolded in three phases, and therefore the LASI-DAD fieldwork was also carried out in phases, recruiting most respondents about 6 – 7 months after the core LASI interview.