In the mid-20th century, William Sheldon developed the idea of somatotypes in explaining different types of criminal behavior. Sheldon defined three body types believed to be associated with criminality: mesomorphs, who are athletically fit; endomorphs, who are overweight, and ectomorphs, who are characterized by fragility and thinness. Sheldon's research implied that mesomorphic individuals were more prone to committing violent and aggressive acts. This research explores a new method of somatotyping using the Body Mass Index (BMI). What follows is an examination of prisoners from the State of Arkansas, using information provided by the Arkansas Department of Correction's database on inmates. In particular, this paper examined prisoners' physical characteristics such as age, height, and weight in comparison to the types of crimes that these prisoners committed. The findings of this paper show that the BMI is a useful alternative to traditional somatotyping techniques; the findings also suggest that a prisoner's somatotype is associated with criminal patterns while being a meager predictor of criminality. Methodological and theoretical implications of this study are discussed. © 2008 Elsevier Inc. All rights reserved.