Summary measures of cardiovascular risk have long been used in public health, but few include nutritional predictors despite extensive evidence linking diet and heart disease. Study objectives were to develop and validate a novel risk score in a case-control study of myocardial infarction (MI) conducted in Costa Rica during 1994-2004. After restricting the data set to healthy participants (n = 1678), conditional logistic regression analyses modeled associations of lifestyle factors (unhealthy diet, decreased physical activity, smoking, waist:hip ratio, low or high alcohol intake, and low socioeconomic status) with risk for MI. Using the estimated coefficients as weights for each component, a regression model was fit to assess score performance. The score was subsequently validated in participants with a history of chronic disease. Higher risk score values were associated with a significantly increased risk of MI [OR = 2.72 (95% CI = 2.28-3.24)]. The findings were replicated in a model (n = 1392) that included the best covariate measures available in the study [OR = 2.71 (95% CI = 2.26-3.26)]. Performance of the score in different subsets of the study population showed c-statistics ranging from 0.63 to 0.67. The new score presents a quantitative summary of modifiable cardiovascular risk factors in the study population.