While it has been proposed that language teachers' beliefs could filter the way they perceive their teaching and influence their practice, few studies have investigated how their beliefs interact with their teaching decisions and why some beliefs override others. When EFL teachers adapt the Western-based Communicative Language Teaching (CLT) model to Asian contexts, tensions between beliefs about different traditions of language teaching begin to surface and influence their perceptions and practice of new teaching methodologies. Therefore, exploring how EFL teachers' beliefs interact with their teaching decisions could shed more light on EFL teacher development. This paper reports on the interactions between a pre-service EFL teacher's beliefs about CLT and her teaching practice in a one-year postgraduate teacher education programme in Hong Kong. Data were collected from semi-structured interviews, belief-inventory questionnaires, researcher's field notes, classroom observations and stimulated recall interviews at different times in the programme. It gives an interpretive account of the participant's reactions to conflicting beliefs and the impact on her learning process. This is followed by a discussion on several characteristics of belief development, which facilitated CLT adaptation and/or hindered teacher development. (Contains 2 notes and 2 tables.)