Language learners and teachers' cognition in respect of learning and teaching plays a critical role in mediating their actual behaviour and decisions in the process. This study investigates the vocabulary learning and teaching beliefs held by pre-service and in-service teachers in Hong Kong and on the Chinese mainland so that teacher education programmes can better equip teachers with appropriate knowledge concerning the vital task of vocabulary teaching. A mixed approach was adopted in inquiring into the nature of vocabulary learning and teaching beliefs held by these participants. Statistical tests (factor analysis, multi-variate analysis, and Chi-square test) were employed in conjunction with qualitative analysis of the data collected. The analyses revealed variations in the beliefs held by the participants in the two contexts. The identified variations in the beliefs held by pre-service and in-service participants both in Hong Kong and on the Chinese mainland were less significant than those that emerged when comparing Hong Kong participants' beliefs with those of their mainland Chinese counterparts. The findings are indicative of profound contextual mediation on the participants' vocabulary teaching and learning beliefs. They also confirm the importance of raising and strengthening language teachers' strategy and language awareness in teacher development programmes. (Contains 4 tables and 1 figure.)