There has been significant focus on multicultural education and particularly culturally responsive teaching (CRT), as classrooms experience an increasing cultural diversity. Within this broader context, this study explores International Baccalaureate (IB) teachers' self-efficacy in a multicultural classroom. This study compares IB teachers with their counterparts in non-IB schools across eight societies. Utilizing large survey data, it was found that IB teachers are, on average, more likely than non-IB teachers to be confident in their ability to teach students from diverse cultural backgrounds. This group difference was statistically significant and was substantial in terms of effect size. Notably, the group difference was identified across all programme (or building) levels and all the eight societies. In contrast, within-group difference in IB teachers' self-efficacy was relatively minimal. The study contributes to scholarly discussions on the role of IB school teachers in practicing and promoting CRT across various societies.