The objective of this paper was to examine whether the Big-Five Personality factors were associated with obesity and 2-year weight gain in Australian adults. The sample included 5265 Australian adults aged 25– 65 years. Binary logistic regression models indicated that Extraversion, Agreeableness and Neuroticism were cross-sectionally associated with obesity, with Conscientiousness inversely associated with obesity. The longitudinal analyses indicated that Extraversion predicted 2-year weight gain. The relationships between personality and obesity/weight gain were not moderated by age or sex. These results have potentially important implications for developing more effective treatment and prevention strategies for obesity.