The objective of this study was to evaluate how weight classification relates to meeting task constraints. Using a cross-sectional design, three-dimensional motion data were collected while children crossed obstacles of various heights. Twelve normal-weight (≥5th and <85th percentile on growth charts) and 12 overweight or obese (≥85th percentile on growth charts) 4- to 13-yr-olds participated. During obstacle crossing, children who were overweight or obese took longer to reach maximum knee height and to achieve foot contact (all P = 0.04). Normal-weight children landed flat-footed after obstacle crossing whereas overweight and obese children landed heel first (P = 0.04). Children had higher coefficients of variation for ankle position at heel contact after crossing medium obstacles (P = 0.02). Slower rates of obstacle crossing and landing heel first after crossing obstacles could be behind higher risks of falls for children who are overweight or obese.