The authors have studied heterogeneity in reporting behavior and its impact on the analysis of self-reports about students' dishonest behavior in schools. Two hundred sixty-five randomly chosen, seventh-grade students (typically 12 years old) from lower secondary schools in Prague 6, a district in the capital of the Czech Republic, participated in this survey. The results of the self-reports, adjusted for heterogeneity, are highly related to students' levels of academic achievement and their parents' education and partly related to their gender, while unadjusted self-reports are only slightly related to the level of parents' education. The authors also show differences in the reporting behavior across diverse subdomains of school behavior and suggest using anchoring vignettes closely related to the domain described in the self-reports.