This study was an investigation of public elementary school students' affective changes through English Activities of international understanding lessons at Japanese public elementary school. The learners' expected affective changes were regarded as "International Posture", "Self-esteem", "Collective Self-esteem", and "Interest in Foreign Affairs" based on theoretical perspectives and the goals specified by Ministry of Education. International Understanding Questionnaire for Children (IUQC), a written instrument to measure elementary school students' "International Posture", "Self-esteem", "Collective Self-esteem", and "Interest in Foreign Affairs" was developed for the study. After the IUQC was validated in terms of its dimensionality, rating scale functioning, and item fit using factor analyses, and Rasch-based analyses, it was administered to 105 public elementary school students (61 fifth graders and 44 sixth graders) at the beginning and end of international understanding lessons in 2006. Results of the two-way mixed factorial ANOVA analyses (trial x grade) indicated that the elementary school students in this study increased their "International Posture" to a statistically significant degree after taking the international understanding lessons for one academic year. The more experienced sixth grade learners performed better on the "International Posture" items on the IUQC than the less experienced fifth graders. The sixth grade participants' "Self-esteem" did not change, while the fifth grade participants' Self-esteem decreased. All participants' "Collective Self-esteem" was not influenced by the lessons. Their "Interest in Foreign Affairs" remained the same both in the beginning and end of the lessons. The influence of "classes" on the four affective constructs was not shown by the two-way mixed factorial ANOVA analyses (trial x class). However, the qualitative analyses indicated that the elementary school students whose teacher actively supported the international understanding lessons showed a number of positive effects in the classroom. This study contributes to affective research in the field of early English education at Japanese public schools. The results of the study partially confirmed the value of English Activities in the international understanding lessons. Further, it demonstrates the effective use of factor analyses and the Rasch-based model to develop a reliable instrument to measure elementary school students' affective constructs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]