OBJECTIVES: To determine which cognitive tests are independently associated with performance on the Timed Up-and-Go Test (TUG). DESIGN: Data were obtained from Wave 1 of The Irish Longitudinal Study on Ageing (TILDA), a population- based study assessing health, economic, and social aspects of aging. SETTING: Community-dwelling adults completed a home based interview and a health center–based assessment. PARTICIPANTS: TILDA participants aged 50 and older with a Mini-Mental State Examination (MMSE) score of 10 or greater (N = 4,998). MEASUREMENTS: Participants completed a battery of cognitive assessments including the Montreal Cognitive Assessment (MoCA), Color Trails Test, word and letter fluency, choice reaction time, sustained attention, prospec- tive memory, word recall, and picture memory. Linear regression was used to determine univariate and multivari- ate associations between TUG and each cognitive test. RESULTS: Slower TUG time was associated with poorer performance on all cognitive tests in univariate analysis (P < .05). In multivariate analysis, poorer performance on the MoCA, letter fluency, Color Trail 1, cognitive reaction time, mean sustained attention response time, and prospec- tive memory were independently associated with slower TUG time (P < .05). CONCLUSION: Slower TUG time is independently asso- ciated with poorer performance on global cognition, exec- utive function, and memory tests and slower processing speed. This highlights that TUG is more than just a simple