Implementation of the first Complex Instruction (CI) based unit developed especially for Latvia focused on the Holocaust. It has provided an opportunity to examine issues of ethnic tolerance among Latvian high school students and teachers. Two independent studies were conducted by the first author to measure the impact of the unit. The first study compared the level of ethnic intolerance among students before and after participation in the CI-based unit activities. Results showed reduced prejudice among this group, but also a decrease within the control group. Analysis of these results pointed to the influence of the history teacher. This teacher taught both groups of students. During interviews, teachers indicated that they had changed as a result of participation in CI seminars and through the use of the CI unit. The teachers stated that they felt an increase in self-esteem, empathy and ethnic tolerance. The aim of the second study was to measure attitude change among a larger group of teachers before and after participation in CI training seminars. Results showed an increase in civic responsibility attitudes. Further analysis indicates that the degree of change is influenced by the amount of exposure to and experience with the new teaching methods.