An evaluation of support needs is fundamental to the provision of services to people with intellectual and developmental disabilities. Services should be organized by considering the support that people need to improve their quality of life and enforce their rights as citizens. This systematic review is conducted to analyze the rigor and usefulness of the available standardized tools for assessing support needs, as well as the uses of their results. Several databases were consulted, including Web of Sciences, Scopus, PubMed, ProQuest Central, PsycInfo, ERIC, and CINAHL, and the 86 documents that met the review criteria were organized into four sections: (a) measurement tools, (b) descriptive/correlational studies, (c) predictive studies, and (d) interventions. The results showed that age, level of intellectual disability, adaptive behavior skills, the number and type of associated disabilities, and medical and behavioral needs affected the support needs of people with disabilities. Quality of life outcomes have been predicted by the individual’s support needs, explaining a significant percentage of their variability. The findings are useful in guiding assessments and planning interventions. Further research should address the effectiveness of specific support strategies and the development of social policies and indicators for inclusion that involve assessing support needs.