Introducing preschool-age children to people of diverse ethnic/racial backgrounds and cultural practices is becoming one of the central features of early educational programming. This study used a pre-test post-test design with a control to assess such an educational intervention aimed at positively influencing American preschoolers' attitudes toward Japanese children. American children's ethnic/racial awareness and attitudes were assessed using multiple measures prior to and after the completion of a 4-month-long cultural exchange program between a preschool in the United States and one in Japan. In comparison to the control group, children participating in the "Sister School" program showed an increase in ethnic/racial awareness and own-group bias after the program's completion. However, children's own-group bias was not related to their evaluation of Japanese children when attitudes toward Japanese were assessed independently of the children's attitudes toward their own group. Thus, while the treatment group children displayed a significant increase in own-group bias on a forced-choice attitude assessment, their evaluation of Japanese on an independent measure was slightly more favorable after the intervention than before; however, this increase on the independent measure did not achieve significance. These finding suggest three important points: (1) teaching preschool-age children about an ethnic/racial out-group raises their awareness of their own group membership; (2) increasing children's investment in their own ethnic/racial group does not automatically translate into their disparagement of out-groups; and (3) preschool-age children's out-group attitudes are not easily influenced. (Contains 41 references.) (Author)