This study was conducted to examine the acquisition of the meaning of the temporal conjunctions "before" and "after." The initial hypothesis was that in the acquisition of a word, the child learns its semantic components one at a time. The subjects were 40 school children attending the Bing Nursery School at Stanford University. The experiment was run with 10 children in each of four age groups, ranging from 3;0 to 5;0 years, who participated in two tasks. The first was a production task designed to elicit certain answers from the children, and the second task tested their comprehension of "before" and "after." The results showed that children not only learn the semantic components one at a time, but in a particular order. Thus, to restate the hypothesis: children learn the meanings of words component by component, and where these components are hierarchially related, the feature hierarchy is learned beginning with the superordinate component. (Author/LG)