Studies have indicated that the level of autonomy of people with intellectual disability is influenced by personal and environmental factors. The aims of this cross-sectional and correlational study were to determine a correlation between the level of autonomy in adults with intellectual disability, on the one hand, and specific personal and environmental factors, on the other hand, and to determine the predictors of the achieved level of autonomy. Adults with mild and moderate intellectual disabilities (N = 128) completed self-report Autonomy subscale of The Arc's Self-Determination Scale: Adult Version and the Choice Questionnaire. Their executive functions were assessed individually. Data on participants' social skills were obtained from their caretakers using the Vineland Adaptive Behaviour Scale - Socialisation domain. The results indicated a significant positive correlation between participants' level of autonomous behaviour and their age, social skills, availability of choice and executive functions. Significant independent predictors of the autonomy level were availability of choice, type of housing, gender and age of the participants. It is concluded that it is important to apply the procedures designed to develop the skills of independent decision-making as well as support the encouragement of independent housing.