["To assess whether preschoolers' performance on a delay of gratification task would predict their body mass index (BMI) 30 years later.", 'In the late 1960s/early 1970s, 4-year-olds from a university-affiliated preschool completed the classic delay of gratification task. As part of a longitudinal study, a subset (n = 164; 57% women) were followed up approximately 30 years later and self-reported their height and weight. Data were analyzed using hierarchical regression.', 'Performance on the delay of gratification task accounted for a significant portion of variance in BMI (4%; P < .01), over and above the variance accounted for by sex alone (13%). Each additional minute that a preschooler delayed gratification predicted a 0.2-point reduction in BMI in adulthood.'] Does preschoolers ' delay of gratification predict their body mass 30 years later?