Autonomous learning behaviour is the avenue to improvement in language ability. In the scope of vocabulary, autonomous learning enables efficient learning, which in turn improves students' ability in the four language skills, namely, listening, speaking, reading and writing. This study was undertaken with the aim of probing how teaching practices affect autonomous learning behaviour in vocabulary development. A case study on 34 students engaged in an English proficiency class at an institution of higher learning was carried out. Data were collected through four rounds of weekly interviews as well as daily journal entries for one month by the students and their lecturer. It was found that the instructor is a crucial mediating variable in encouraging autonomous learning behaviour. Some of the practices which impact students positively are providing the right pedagogical context, teaching according to students' needs and interest and providing adequate assistance in materials used in class. When teacher is able to set the right learning climate, positive states and mental readiness in learning are witnessed, which are requisites to autonomous learning behaviour. However, it is also important for the instructor not to overburden students with too many words in one lesson. For the students, it is necessary to reduce dependence on the instructor and take greater charge in the learning process to become autonomous language learners.