Objective: The objective of this study is to (a) examine racial/ethnic differences in trajectories of cognitive function and (b) evaluate the role of education and health behaviors (physical activity [PA] and smoking) as mediators of racial/ethnic differences in the rate of decline in cognitive function in older adults. Method: Data for this study came from the Health and Retirement Study (n = 3,424). Hierarchical linear models were used to define the trajectory of cognitive function between 2002 and 2008. Participants were classified based on PA as non–vigorously active, intermittent vigorously active, and consistently vigorously active. Results: After adding education, the Hispanic’s and Black’s disparities in cognitive performance were slightly attenuated (Hispanics, β = –1.049, p < .001; Blacks, β = –3.397, p < .001) but were still different from Whites. Smoking was not associated with the cognition intercept or rate of decline. Discussion: We found education had a partial mediating effect on racial differences in levels of cognition but not on the rate of change over time.