This research investigates positive future expectancies, particularly hope in children, which is comprised of agency thinking, perceiving oneself as capable of achieving goals, and pathways thinking, perceiving oneself as capable of discovering methods toward the desired goals. Two studies (n = 82) were conducted in the United States to examine the role of agency and pathways thinking in children's trait and state happiness based on children's self-reports and their parents reports of their children. In Study 1, dyads of typically developing children (M[subscript age] = 10.21 years) and their parents (M[subscript age] = 43.84 years) completed measures of hope and happiness. Study 2 extended Study 1 to include a diverse sample of children with chronic health conditions (M[subscript age] = 11.14 years) and their parents (M[subscript age] = 43.48 years). In Study 1, regression analyses revealed that children's self-reports of agency thinking predict children's trait and state happiness, p's < 0.05. Contrastingly, in Study 2, regression analyses revealed that children's self-reports of pathways thinking predict children's self-reports of trait happiness, p < 0.001. Also, collectively, pathways thinking, agency thinking, and children's age predict children's state happiness, p = 0.025. In both studies, parents' reports of their children's hope were not significant predictors of children's happiness. There also was not an association between parents' perceptions of their children's hope and happiness and their children's self-reported levels. These findings elucidate the cognitive aspects of hope that promote happiness in childhood and advance understanding of the determinants of children's happiness in the U.S.