This study aims to explore the influence of science teachers' beliefs on an educational assessment reform adopted in Estonia. Two existing questionnaires were adapted to develop a model to examine teachers' beliefs about teaching and assessment and administered to a sample of Estonian science teachers (N = 319). The outcomes were examined through confirmatory factor analysis (CFA) and structural equation modelling (SEM). This produced two dominant beliefs in relation to teaching named "teacher-centred" and "student-centred", plus indicating four purposes for assessment, namely: "teaching improvement", "irrelevance", "examination", and "school and teacher accountability". Findings indicate most Estonian science teachers express beliefs aligned with student-centred approaches and predict positively teaching improvement purposes for assessment as perceived by teachers, both of which seem to support the implementation of a student-centred reform in the country. However, at the same time, the relatively high rating of teacher-centred beliefs and high valuation of assessment for examination purposes seem to counteract the intended reform.