support the hypothesis that feelings of appreciativeness play a main role in encouragement prosocial behavior in Thai youth. In addition, in both groups perception of cost of benefactor and gain of recipient positively related to feelings of appreciativeness, but desirability of act and obligation of benefactor insignificantly related to feelings of appreciativeness. These results partially support hypothesis about cognitive factors that can affect feelings of gratitude. Our findings are consistent with the previous study focusing on the effect of costs and benefits in determining the intensity of gratitude (Tesser et al., 1968; Trivers, 1971).