The Towers of Hanoi (ToH) and London (ToL), historically held as isomorphic measures of problem solving, have had their equivalence questioned in recent years. Adult studies that equalized administration and task structure have found increased correlation between Towers, but insufficient evidence exists regarding whether the same results would be found in young children. This study examined 29 typically developing preschoolers. Both Towers, along with four measures of executive function, were administered in two sessions. The Towers were strongly correlated, but the strength of this relationship was impacted by discontinuation type (i.e., quit vs. standardized), and analyses revealed differences in sustained attention and Tower correlations for those who quit. Complex Tower items showed stronger correlations, and Tower performance and visuospatial WM were also highly correlated. Overall, these results suggest that the Towers, when equated in administrative and structural features, are interchangeable measures of problem solving in preschoolers. / Graduate / 0621 / 0620 / 0622 / jsheehan@uvic.ca