Effective teaching is a key factor in educational effectiveness and improvement. To facilitate the knowledge exchange regarding effective teaching in secondary education internationally, there has been a growing interest in using classroom observation measures. However, little is known regarding the comparability of observation measures across various national contexts (measurement invariance). Consequently, comparing effective teaching behaviour across contexts is compromised by issues of construct and measurement equivalence. In the present study, we investigated measurement invariance of the International Comparative Analysis of Learning and Teaching (ICALT) for measuring teaching behaviour across various national contexts including the Netherlands, South Korea, South Africa, Indonesia, Hong Kong-China, and Pakistan. Results showed that ICALT indicates full strict invariance in four out of the six countries, which provides a possibility to compare teaching behaviour in the Netherlands, South Korea, South Africa, and Indonesia. South Korea indicated the highest quality of teaching behaviour, while Indonesia indicated the lowest.