The objective of this study was to determine the prevalence of and possible risk factors for overweight in a sample of 5- to 6-year-old Hispanic (predominantly Mexican American) children in Chicago, Illinois, to see if overweight is more common in more highly acculturated immigrant families. There were 250 kindergarten students (92% of those eligible) attending two public elementary schools serving primarily Mexican American neighborhoods measured for height and weight. Consenting mothers were interviewed (n=80) and measured (n=38). The interview tool covered demography, acculturation, infant and toddler feeding practices, current cating patterns and food preparation habits, physical activity, and psychosocial family characteristics. Overweight was conservatively defined as weight-for-height at or above the National Center for Health Statistics 95th percentile. The data were used to describe the prevalence of overweight. Overweight and nonoverweight children were compared on all survey variables using appropriate statistical tests, with significance set at .05. There were 23% of the total sample of children (n=250) and 26% of the subsample of children (those whose mothers were interviewed) who were overweight. Analysis limited to children in the subsample explored risk factors. The median score on the Acculturation Scale was 4.0 (range 2.4–10.4) on a scale of 2.4 (entirely not acculturated) to 12 (fully acculturated). There was no significant association between overweight and Acculturation Scale score. Overweight children were more likely than those not overweight to watch television for more than 3 hours during weekend days (48% vs. 22%, P=.03). Overweight children were also more likely to consume sweetened beverages (powdered drinks, soda pop, atole) daily (67% vs. 39%, P=.03). There was a trend indicating that free access to food at home increased the risk of overweight (P=0.06). No other family- or child-level variables were related to overweight. Only 40% of mothers with an overweight child correctly assessed these children as overweight. Approximately one quarter of the children in the study were overweight. Our hypothesis that their obesity was linked to acculturation was not confirmed. Longer hours of child television viewing on weekends and higher levels of sweetened beverage consumption were important behaviors associated with the occurrence of overweight. These data should be considered when designing future studies in this population.