The purposes of this research were to study concepts of happiness of Thai children in term of intrinsic and extrinsic answers during the individual interview. Three concepts of happiness were included in this study; Definitions of happiness, characters of a happy person, and causes of happiness. Participants were 176 Thai students from kindergarten, third grade, and sixth grade, from divorced and traditional families. The results showed developmental trend in children’s concepts of happiness. The older the children, the higher percentage of intrinsic answers on definitions of happiness (F(2, 166) = 4.09, p < .05) and characters of a happy person (F(2, 172) = 30.66, p < .001). There was no age trend found for causes of happiness with the result clearly showed very high percentage of extrinsic answers for all group. Only one difference on concepts of happiness between family groups was found in this study. The children from divorced family had significantly higher percentage of intrinsic answer on the characters of a happy person. (t(173) = 2.27, p < .05).
