Self-determination is a key construct to ensure the development of skills that enable individuals with Autism Spectrum Disorder (ASD) to take control of their lives. However, the study of self-determination-related skills in adults with ASD remains limited. This research aims to examine the levels of self-determination of 189 adults with ASD between 30 and 75 years old, as well as the personal or environmental factors related to these levels. Data were collected using an ad hoc scale developed from the Functional Model of Self-Determination. Most participants have a low level of self-determination, especially regarding empowerment-related skills. Factors such as age, type of support, or socioeconomic level affect these levels. There is also an inverse association between the level of ASD and certain self-determination skills. Adopting a comprehensive approach that promotes self-determination can significantly improve the quality of life for adults with ASD. This involves not only identifying factors that influence self-determination but also designing interventions that address the individual and contextual needs of each person with ASD.