The purpose of this study was to measure the development of forethought in children as a function of age, thereby documenting a normal use of this facility. It was hypothesized that forethought would develop on a continuum increasing with age, with no significant differences due to sex of the child. To test this hypothesis, items were pooled which were related to children's development of five capabilities: future time comprehension, the comprehension of death, the understanding of real time consequences, the understanding of cyclic variations in the natural environment, and anticipation of important future events. One preliminary multidimensional questionnaire consisting of the pooled items was used; the questionnaire was prescreened and adjusted for vocabulary level across ages and was read aloud, if necessary, to the youngest subjects. Subjects were 300 children ranging in age from 3 through 14 years who attended schools in the San Francisco Bay area. Six groups, each spanning 2 years of the age range, were formed. Results, which support the hypothesis and reveal that future time comprehension was the most important factor of those studied, are discussed. Related materials, including data tables, are provided in appendices. (RH)