The aim of this study was to examine the relationship between dietary patterns and caries experience in a representative group of low-income African-American adults. Participants were residents of Detroit, Michigan, with household incomes below 250% of the federally-established poverty level (n = 1,021). Dietary histories were obtained by trained interviewers in face-to-face interviews with the adult participants, using the Block 98.2 food frequency questionnaire. Caries was measured by the ICDAS criteria (International Caries Detection and Assessment System). There were 200 dietary records whose data were judged to be invalid; these participants were omitted from the dietary analyses to leave n = 821. Factor analysis identified patterns of liquid and solid food consumption, and the resulting factor scores were used as covariates in multivariable linear regression. Caries was extensive, with 82.3% of the 1,021 participants (n = 839) having at least one cavitated lesion. Nearly three quarters of the adult participants were overweight or obese. This population had severe caries, poor oral hygiene, and diets that are high in sugars and fats and low in fruits and vegetables. Apart from tap water, the most frequently consumed food item by adults of all ages was soft drinks; 19% of all energy from sugar came from soft drinks alone. In both the bivariate analyses and in the regression model, frequency of soft drink consumption and the presence of gingival plaque deposits were significantly associated with caries. Interventions to promote oral health are unlikely to be successful without improvements in the social and physical environment.