This paper examines the hypothesis that St. Lucian primary school teachers' science teaching and learning beliefs and their applicability beliefs are stronger predictors of their science teaching strategies than their teacher education experiences. Quantitative procedures were used where the level of each belief construct as well as their underlying constructs was measured in each teacher in the population and a determination made as to their favourability towards inquiry-based instruction (IBI). The levels of a sample of these teachers' IBI practices were also determined using an observational rating scale. Multiple regression analyses were used to determine the extent to which teachers' beliefs serve as predictors of their IBI practices. The results showed that teachers' applicability beliefs were barely moderately favourable to their practice of IBI, while their beliefs about science teaching and learning were favourable. Their inquiry-based practices were found to be at the unsatisfactory developing inquiry level. While their science teaching and learning beliefs were found to be significant and moderately positive predictors of their inquiry-based instructional practices, their applicability beliefs seemingly functioned as a moderating variable that limited the effect of teachers' favourable science teaching and learning beliefs on their instructional practices. These findings are significant in that they show the detrimental effect school-based factors can have on teachers' instructional practices in science.