Using the 1997-2004 National Health Interview Survey (NHIS), we examine changes in chronic conditions as explanations for recent declines in late-life disability prevalence. Building on prior studies, we decompose disability declines into changes in the prevalence of chronic conditions and in the risk of disability given a condition. In doing so, we extend traditional decomposition techniques to take advantage of the annual data points in the NHIS. We then repartition these traditional decomposition components into causal and co-morbid components based on respondents’ reports of conditions causing disability. We find a general pattern of increases in many chronic conditions accompanied by declines in their association with disability. However, only 2 of the 7 condition groups that we examined—heart and circulatory conditions and sensory impairments (specifically, vision impairments)—were less likely to cause disability in 2004 than they were in 1997. Out of a total decline in disability prevalence of 1.45 percentage points, declines in heart/circulatory conditions causing disability account for .92 percentage points and declines in vision impairments causing disability account for .59 percentage points. We discuss our findings in light of improvements in treatments and changes in the environments of older adults.