The main goal of the study was to describe and understand the development of beliefs related to the thinking and decision-making made by five teachers in teaching chemistry during a two-year intervention study. The participating teachers implemented and, in the second year of the study, developed teaching modules which were geared to the promotion of students' scientific and technological literacy (STL). By means of this intervention, it was hoped to induce change in chemistry teachers' beliefs towards a STL approach. This was expected to involve a shift from beliefs related to more traditional teaching styles, with stronger emphasis on eliciting students' extrinsic interest, into emphasising student centred approaches and students' intrinsic motivation. In order to recognise and identify the teacher beliefs, data were gathered before and during the intervention by means of teacher interviews and classroom observations. These were used to identify teacher beliefs as core (both stated and enacted), peripheral (stated by not enacted), or emerging (newly stated beliefs coming from the intervention). In general it was possible to identify teacher beliefs based on specific components and to further classify them as positive or negative. It was further identified that these beliefs could be related to core, peripheral and emerging beliefs. (Contains 2 tables.)