The ability to derive the meanings of words from supportive story contexts was studied in 45 seven-eight-year-olds. Children read short stories each containing a different novel word and defined the word at the end of each story. There were three intervention sessions. One group was asked to justify their definition and subsequently received feedback on its accuracy. A second group was given feedback first and asked to explain how the experimenter knew the correct answer. A third (control) received feedback only. In general, practice lead to improved performance, with an increased number of children in all groups using the story context to derive meanings for the novel words in a post-intervention test. Children in the two explanation groups made the greatest gains in definition accuracy. The implications for teaching vocabulary learning skills are discussed.