The Taiwan Initiative for Geriatric Epidemiological Research (TIGER) was founded in 2011 to elucidate the interrelationships among various predictors of global and domain-specific cognitive impairment, with the aim of identifying older adults with an increased risk of dementia in the preclinical phase. TIGER, a population-based prospective cohort, recruited 605 and 629 (total of 1,234) older adults (aged 65 and above) at baseline (2011-2013 and 2019-2022) of phase I and II, respectively. Participants have undergone structured questionnaires, global and domain-specific cognitive assessments, physical exams, and biological specimen collections at baseline and biennial follow-ups to date. By 2022, TIGER I has included 4 biennial follow-ups, with the participants comprising 53.9% female and having a mean age of 73.2 years at baseline. After an 8-year follow-up, the annual attrition rate was 6.1%, reflecting a combination of 9.9% of participants who passed away and 36.2% who dropped out. TIGER has published novel and multidisciplinary research on cognitive-related outcomes in older adults, including environmental exposures (indoor and ambient air pollution), multimorbidity, sarcopenia, frailty, biomarkers (brain and retinal images, renal and inflammatory markers), and diet. TIGER’s meticulous design, multidisciplinary data, and novel findings elucidate the complex etiology of cognitive impairment and frailty, offering valuable insights into factors that can be used to predict and prevent dementia in the preclinical phase.