The purpose of the study was to investigate factors associated with overweight and obesity among Kuwaiti children aged 3-5 years. A cross-sectional sample of 3473 pupils (1748 boys and 1725 girls) was selected for the study from kindergartens using a multi-stage random sampling technique. Overweight and obesity were defined as weight-for-height (W/H) > or = 90th-< 95th and > or = 95th centiles of the NCHS/CDC reference population, respectively. Questionnaires were used to obtain information about birth order, parents' education and occupation, family income, number of servants, eating habits, grandparents and number of persons living at home, number of siblings, socioeconomic status (SES), which was based on parents' education and occupation, family income, area of residence and number of servants. Weight and height were measured and the pupils' dental status was assessed. Factors that were found to be significantly associated with overweight and obesity were gender, age, region (governorate), parents' education, birth order, dental status, eating regular meals and SES. Factors that were significantly associated with overweight and obesity males were age, governorate eating regular meals, number of persons living at home and SES. Among females these factors were governorate, dental status, number of servants and SES. The logistic regression analysis showed that the same factors shared by both genders significantly contributed to the development of overweight and obesity except father's education. This study concludes that ecological factors play an important role in the development of overweight and obesity, especially those related to affluence; Kuwait has been undergoing modernization and increasing affluence and changes to sedentary lifestyle and increased food consumption may have contributed to changes in overweight and obesity among the children.