Chronic kidney disease (CKD) is a major public health problem with increasing incidence and prevalence in North America and worldwide. CKD disproportionately affects the elderly, and leads higher risks of kidney failure, cardiovascular events and all-cause mortality. In this population, CKD is also associated with additional comorbid conditions, and an increased prevalence of frailty and disability. Frailty is a multidimensional syndrome characterized by loss of lean body mass (sarcopenia), weakness, and decreased endurance, leading to reduced activity and a poor response to stressors. Several prospective studies in the general population have shown that measures of frailty are strongly associated with death and hospitalization in older individuals, and moreover that this association is independent of other clinical risk factors and comorbid conditions. We believe that frailty is highly prevalent in patients with CKD, and is associated with treatment decisions and outcomes. In order to explore this hypothesis, we are presently conducting a prospective cohort study examining frailty in individuals with advanced CKD. Our study will enroll 600 patients with CKD Stages 4-5, and perform tests of physical function and cognition. We will then associate frailty and its components (physical function, cognition, depression) with treatment preferences and adverse outcomes in the CKD population. The study has recruited 395 patients to date, and recruitment for the baseline visit will continue through 2015. We will perform cross sectional analyses in the summer of 2015, and will examine associations with outcomes in 2016.