There are very few studies on the relationship between cognitive ability and dental status in middle aged and younger adults. We postulate that lower cognitive ability is directly related to poorer dental status and that this relationship operates through the relationship between cognitive ability and health-related behaviors. The objectives of this study are (1) to examine the relationship between two measures of cognitive ability, Symbol Digit Substitution Test (SDST) and Serial Digit Learning Test (SDLT) and decayed, missing, filled and sound tooth surfaces, (2) to examine the relationship between cognitive ability and two health-related behaviors, dental visits and smoking, (3) and to test if the aforementioned relationship is independent of socioeconomic position. Data were from the Third National Health and Examination Survey. We examined the relationship between SDST and SDLT, and the oral health indicators and the behavioral factors using a series of regression models. Individuals with lower cognitive ability had higher means of decayed and missing tooth surfaces and lower means of sound and filled tooth surfaces. Poorer cognitive ability was associated with poorer behaviors; lower levels of dental attendance and higher levels of smoking. The relationship between cognitive ability and dental status was further demonstrated in the regression analysis. For a higher unit of SDST the rate ratio for decayed tooth surfaces was 1.91 (CI 1.53-2.38) which attenuated to 1.40 (CI 1.13-1.73) after adjusting for age, sex, ethnicity, income, dental attendance and smoking, but remained significant. Similar results were obtained for all oral health outcomes. This study found a relationship between cognitive ability and dental status and related behaviors among middle aged and younger adults. The relationship was independent of income and ethnicity. These findings support the theories put forward on a relationship between cognitive ability and health operating through health-related behaviors. (Contains 3 tables and 3 figures.)