Our aim was to analyze the variables associated with adherence to the Mediterranean diet in the adult population. We conducted a cross-sectional study in an established cohort of 1,553 healthy study participants (mean age=55±14 years; 60.3% women). Mediterranean diet adherence was evaluated based on a 14-item questionnaire and the Mediterranean diet adherence screener, which defines adequate adherence as a score of ≥9. Physical activity was evaluated using the 7-day physical activity record. Sociodemographic, biological, and anthropometric variables were also evaluated. The differences between Mediterranean diet compliers and noncompliers are defined by the consumption of fruit, red meats, carbonated beverages, wine, fish/shellfish, legumes, pasta, and rice (P<0.01). Adherence was lower among individuals younger than 49 years of age. In the first age tertile, adherence was greater in women and in nonobese individuals, and the triglyceride levels were lower among compliers. In the second age tertile, the compliers exercised more and had a lower body fat percentage. In the third age tertile, the compliers also possessed less body fat. The logistic regression analysis revealed the following factors associated with improved Mediterranean diet adherence: more physical exercise (odds ratio=1.588), older age (odds ratio=2.162), and moderate alcohol consumption (odds ratio=1.342). The factors associated with improved Mediterranean diet adherence included female sex, age older than 62 years, moderate alcohol consumption, and more than 17 metabolic equivalents (METs)/h/wk of physical exercise. Poorer adherence was associated with males and obesity.