In 1969, 48% of students walked or biked to school. By 2001, that proportion had fallen to 15%. Increasing children's active travel to school is important for a variety of reasons, including the rising rates of childhood obesity and increasing fuel costs. Recent studies indicate that elements of the built environment affect the amount of time people engage in physical activity. This study evaluates two indicators of the urban form as measures of walkability potential: street connectivity and residential density around elementary schools in Pasco and Hillsborough counties in Florida. By means of controlling for school age on the basis of the growth management legislation history in Florida, four growth eras are compared. Pedestrian sheds of 1/2- and 1-mi radii around school points are used as study areas. These indicators offer insight into the evolution of the urban form around elementary schools and its implications for students' ability to walk to school. Preliminary findings suggest that walkability indicators in the vicinity of elementary schools built before 1950 exhibited high levels of street connectivity and residential density. These values declined consistently until stricter school planning legislation was enacted, when values started to increase and sometimes approached pre-1950 levels. This pattern is stronger, however, in Hillsborough County.