Progressive physical frailty and cognitive decline in older adults is associated with increased risk of falls, disability, institutionalization, and mortality; however, there is considerable heterogeneity in progression over time. We identified heterogeneous frailty and cognitive decline trajectory groups and examined the specific contribution of health conditions to these trajectories among older Mexican origin adults. We use a sample from the Hispanic Established Population for the Epidemiological Study of the Elderly (HEPESE) with at least two measures of frailty criteria during 18 years follow-up: slow gait, weak handgrip strength, exhaustion, and unexplained weight loss (n = 1362, mean age 72). Cognition was measured using the Mini-Mental State Examination (MMSE). Using group-based trajectory models we identified three frailty groups-non-frail (n = 331), moderate progressive (n = 855), and progressive high (n = 149)-and three cognitive decline groups-non-cognitively impaired (476), moderate decline (677) and rapid decline (n = 209). The probability of membership in a high-frailty group given membership in a progressive cognitive decline group was 63%, while the probability of being in a non-frail group given membership in a non-cognitively impaired group was 68%. Predictors of membership into both the progressive high frailty and rapid cognitive decline groups combined were low education and diabetes. Weekly church attendance was associated with a 66% reduction in the odds of being in the combined groups. Interventions to reduce frailty rates and cognitive decline might focus on the management of underlying chronic disease and on increasing participation in activities outside the home.