There are always concerns about teaching quality worldwide. However, there has not been any systematic qualitative or quantitative study in the context of immersion education, as a form of content-based language teaching (CBLT), about the content-language teaching strategies from content-trained teachers with differing levels of L2 respectively. This qualitative study aims at providing rich descriptions about the content-language teaching strategies used by three content teachers with different L2 levels in Hong Kong. Hence, the study can provide insights into whether there is a need to adjust the current requirement for the immersion education teachers in Hong Kong; such teachers are only required to have achieved Band 6 from the International English Language Testing System (IELTS). Also, with the traditional wisdom that good English means good content-language teaching, the study explored the possible relationships between Hong Kong’s immersion education teachers’ L2 levels and the content-language teaching strategies adopted by such teachers.The three teachers of the study had three different English proficiency levels: an advanced level, an upper intermediate level and an intermediate level respectively. The students of the three teachers were from the same high school class from a local secondary school in Hong Kong. The three teachers involved were from three different subjects but the teaches had similar backgrounds in terms of teaching experience, teacher training, specialised content subject training. The three teachers had not received any training about immersion education.As a constructivist grounded study, this research made use of lesson observation and also stimulated recall interviews. The lessons from the three teachers were not only observed but also recorded. There was lesson observation time equivalent to 5 single lessons (each lasting for 40 minutes) from each teacher; saturation was reached after the fifth lesson was observed from each teacher.