The Supports Intensity Scale (SIS) is used to determine the profile and intensity of the supports needed by a person to participate successfully in major life activities. With its publication into 13 languages, a need has arisen to document its reliability and validity across language and cultural groups. Here we explain the adaptation and the validation process of the SIS on a Spanish sample of 885 people with intellectual disability. Results of the study are discussed in terms of the reliability and validity of the SIS on the Spanish sample and its efficacy for multiple uses in Spain.