According to self-determination theory, employees' well-being is related to the autonomy-supportive style of a supervisor. However, the effect of supervision style on well-being remains understudied in low-skilled occupations. This study employed a mixed-method, multi-level approach to examine the impact of autonomy-supportive training (AST) on supervisors and employees and to identify factors contributing to the maintenance of supervisors' autonomy support (SAS). The quantitative phase evaluated the effect of AST on supervisory style and employees' well-being, with a sample of 44 supervisors and 240 employees in New Zealand. The qualitative phase used focus groups and interview with 15 supervisors to explore factors that could influence the maintenance of SAS. Overall, supervisors can be trained to adopt an autonomy-supportive style, but these skills can also be diluted by organisational factors such as pressures and managerial behaviour. This study contributes to autonomy-supportive style research in order to account for factors affecting the maintenance of SAS in low-skilled occupations.