The purpose of this study was to investigate short-term changes of frailty in adults and identify predictors of frailty and disability changes between baseline and the follow-up. A cohort study was conducted in 85 adults with intellectual disability (ID) in southern Taiwan. Variables of frailty phenotype, Barthel Index, fall, comorbidity, and hospitalization were measured at baseline and at a 9-month follow-up. Descriptive statistics, correlations, and generalized linear model technique were used for data analysis. The percentages of frailty and pre-frail conditions were high at baseline. Improvement or deterioration on frailty was noticed in 37.6% of participants. Disability and comorbidity were significant predictors to changes in frailty, and severity of ID and frailty conditions were significant predictors to changes in disability.