The aim of this study is to analyze the determining factors and processes associated with changes in self-determination of people with intellectual and developmental disabilities (IDD) and extensive support needs who moved to ordinary homes within the community. A repeated measures design was carried out, collecting data of 54 participants before the transition and 6 months after. Partial least square-structural equation modelling (PLS-SEM) was used to examine complex relationships between variables to estimate the models. After transition, participants' levels of self-determination, received supports, and choice significantly increased. The effect that received supports had on self-determination was fully mediated by choice, meaning that if supports are not geared towards facilitating autonomy in daily decision making, there will be no improvement in quality of life.