BACKGROUND: Healthy diets have been associated with better cognitive function. Socioeconomic factors including education, poverty, and job complexity may modify the relationship between diet and cognition. METHODS: We used adjusted linear mixed models to examine the association between long-term adherence to the Mediterranean-Dietary Approaches to Stop Hypertension - Intervention for Neurodegenerative Delay (MIND) diet and cognitive function over 8 years of follow-up in Puerto Rican adults residing in the Boston, MA area (aged 45-75 years at baseline). We also examined whether the MIND diet-cognition association was confounded or modified by socioeconomic measures. RESULTS: In both cross-sectional and longitudinal analyses the highest, versus lowest, MIND quintile was associated with better cognition function (β = 0.093; 95% CI: 0.035, 0.152; p trend = .0019), but not with cognitive trajectory over 8 years. Education <=8th grade (β = -0.339; 95% CI: 0.394, -0.286; p < .0001) and income-to-poverty ratio <120% (β = -0.049; 95% CI: -0.092, -0.007; p = .024) were significantly associated with lower cognitive function, while higher job complexity (β = 0.008; 95% CI: 0.006, 0.011; p < .0001) was associated with better cognition function. These variables acted as confounders, but not effect modifiers of the MIND-diet-cognitive function relationship. CONCLUSION: Adherence to the MIND diet was associated with better cognitive function at baseline and over 8 years of follow-up; however, MIND diet was not associated with 8-year cognitive trajectory. More studies are needed to better understand whether the MIND diet is protective against long-term cognitive decline.