Description styles of mothers and preschool teachers in Japan and the U.S. are compared in a referential communication task situation, and their relationship to children's communication task performance is investigated. Mothers and preschool teachers are asked to describe one of a set of four pictures to four-year-old children. Children are asked to choose the target picture described. The type of description is analyzed in terms of two criteria: a literal vs. an imaginative description and a novel vs. a repetitive description. The results show that the differences in description styles are larger between mothers and teachers in Japan than in the U.S. The relationship between their description styles and children's communication task performance is similar in both countries.