To examine whether there is a relationship between psychological stress in the family and obesity in 5- to 6-year-old children.A total of 7443 Swedish families reported on psychological stress across 4 domains as part of the prospective All Babies in Southeast Sweden-project (ABIS). Domains assessed included serious life events, parenting stress, lack of social support, and parental worries. These variables were summarized in cross-sectional and longitudinal composite measures of psychological stress. Logistic regression models were used to calculate odds ratios for childhood obesity for psychological stress.A total of 4.2% of the children were obese according to age-adjusted international standards. Children from families that reported stress in at least 2 of the 4 domains assessed had significantly higher adjusted odds ratios (OR) for obesity, both cross-sectionally (OR, 2.1; 95% CI, 1.3-3.5; P < .01) and longitudinally (OR, 2.6; 95% CI, 1.3-5.4, P < .01).Psychological stress in the family may be a contributing factor for childhood obesity. This finding underscores how important it is to give children with obesity and their families psychological and social support in addition to recommendations about changing life style.