<p>Junior doctors’ motivation and well-being benefit from a safe environment where they can practice with and learn from clinical experiences. Supervising consultants are key figures in this environment by providing safe patient care, but also by supporting junior doctors in their professional development and learning. However, many junior doctors suffer from distress, which suggests that their needs are not optimally met in postgraduate medical education. Self-Determination Theory (SDT) states that a social environment that supports basic psychological needs of learners results in better learning and promotes their well-being. However, there is a theoretical debate whether individual differences, such as need strength, may also influence how learners, such as junior doctors, perceive the environment. A better understanding of the combined role of the environment and individual preferences is relevant to tailor supervision styles to promote motivation and well-being of junior doctors. This secondary analysis of an experimental vignette study on (de)motivating supervision styles examined whether junior doctors’ individual differences in work-related need strength modified the appraisal and effects of consultants’ supervision styles. The analysis included 150 junior doctors (<i>M</i>_<i>age</i> = 29.81, 73.3% female) and showed that supervision style impacted junior doctors’ positive and negative affect through need satisfaction and need frustration, respectively. Junior doctors’ work-related need strength did not modify these effects. These findings underline the importance of considering both need satisfaction and frustration as underlying mechanisms for explaining well-being in Postgraduate Medical Education. Furthermore, the lack of moderation of work-related need strength endorses the principle of universality underlying SDT.</p>