ABSTRACT. This study investigated pre-service and in-service English teachers' efficacy beliefs about teaching English at primary schools in Turkey by revealing the teaching aspects that they felt most and least efficacious. The study also attempted to understand pre-service teachers' views about the effectiveness of pre-service teacher education and explore which major problems in-service teachers encountered while teaching English at primary schools. The quantitative and qualitative data were collected from 170 pre-service and 129 in-service teachers through a questionnaire. The quantitative and qualitative data were analysed using descriptive statistics and content analysis, respectively. According to the findings, both groups held similar positive or negative efficacy beliefs about most teaching aspects: while they reported feeling most efficacious in 'using visual materials', 'giving simple instructions', and 'using gestures, facial expressions and body language effectively', they reported feeling least efficacious in 'using mainly kinaesthetic activities', 'managing class time effectively', and 'knowing how each language skill can be developed'. Pre-service teachers agreed that the 'teaching practicum' was the most ineffective aspect of the programme, followed by 'lack of practice-based courses', 'inadequate number of teaching English to young learners courses', and 'language courses'. In-service teachers reported having problems because of 'limited class hours', 'poor textbooks', 'lack of technological resources', 'lack of learner preparedness', 'lack of learner motivation', and 'large classes'. In the light of these findings, implications were generated to improve the effectiveness of pre-service and in-service teacher education, which could increase the quality of education for English language students at primary schools.