Teachers are key actors who shape the learning environment and whose main tasks include motivating students to learn. Teachers can differ in the way in which they try to motivate students to learn and their motivational strategies can vary from autonomy-supportive to controlling. The present study explored how teachers' personal beliefs and contextual factors relate to their self-reported autonomy-supportive or controlling motivational strategies. Nine grade six teachers at schools with varying student populations were interviewed. Based on their self-reported motivational strategies, two clusters of teachers were distinguished: teachers who mainly reported autonomy-supportive strategies and teachers who mainly reported controlling motivational strategies. The strategies of autonomy-supportive teachers aligned well with their personal beliefs and preferences, whereas some teachers in the controlling cluster would prefer more autonomy-supportive strategies. Underlying reasons for more controlling teaching strategies were mainly contextual, including "factors from above" such as national standards or high-stakes testing, but mainly "factors from below" referring to negative perceptions of students' abilities, behaviour, background characteristics or motivation. Implications are drawn and suggestions for further research are provided.