The Tower of London procedure (TOL) is being utilized increasingly in clinical and experimental contexts, although there is considerable variation in how it is administered and scored. The procedure detailed here was developed using Shallice's original problems and, along with the Porteus Maze Test (PMT), was administered to 205 elementary school students and 74 young adults. TOL scores increased with age in a linear fashion, and the performance of the sixth, seventh, and eighth grade subjects were not statistically different from the young adults. The TOL was moderately correlated with the PMT suggesting that these procedures share a planning component. These data provide initial developmental standards, and the materials, administration, and scoring procedures documented here provide a standard method for utilization of this instrument.