The present study examined the connection between cognitive development and childhood worry. A sample of normal children aged 3-14 years (N = 248) were interviewed about the presence and content of a personal worry. Furthermore, a worry elaboration score was obtained by encouraging children to think up potential negative outcomes associated with a series of worry topics. Finally, a number of Piagetian conservation tasks were administered in order to reliably assess the childrens' level of cognitive maturation. Results showed that there were positive associations among age and cognitive development, worry elaboration, and the presence of a personal worry. Correlational and regression analyses suggested a mediational model in which increased age and, in its wake, cognitive development lead to enhanced worry elaboration which, in turn, increases the possibility of a personal worry to emerge.