Purpose: Patients with spinal muscular atrophy (SMA) suffer from slowly progressive weakness of axial, respiratory and proximal muscles, leading to restrictions in activity and participation. This study aims to investigate patients' level of psychological well-being, using the International Classification of Functioning model and self-determination theory as theoretical frameworks. Materials and methods: In this cross-sectional study, adults with SMA were invited to complete a questionnaire. Instruments to assess psychological well-being included the Satisfaction with Life Scale, the Rosenberg Self-Esteem Scale and the Positive and Negative Affect Scale. Hierarchical lineal regression analyses were performed to investigate the contribution of participation (International Classification of Functioning model) and satisfaction of the need for autonomy, competence and relatedness (self-determination theory) to well-being. Results: Ninety-two respondents (67%) returned the questionnaire. Levels of psychological well-being were comparable to that of healthy reference samples. Well-being was unrelated to sociodemographic variables or illness characteristics. By contrast, well-being was closely related to respondents' satisfaction with participation, and their sense of autonomy, competence and relatedness. Conclusions: This study illustrates the relevance of psychological needs for understanding well-being of individuals with SMA. Supporting patients in meeting their psychological needs should become an objective of person-centred care for this population. ä IMPLICATIONS FOR REHABILITATION Spinal muscular atrophy is a rare inherited disease, characterized by slowly progressive muscle weakness. Psychological well-being, including satisfaction with life, self-esteem and emotional functioning of adults with spinal muscular atrophy appears very comparable with that of healthy reference samples. In line with the International Classification of Functioning framework, well-being in adults with spinal muscular atrophy may be improved by increasing their (satisfaction with) participation. Moreover, clinical assessment and management should focus on optimizing patients' satisfaction with their basic psychological needs (autonomy, competence, relatedness), as this is strongly related to indices of psychological well-being.