The International Association for the Study of Intellectual and Developmental Disabilities (IASSIDD) was established in the early 1960s with the mission of advancing research in the field of intellectual disabilities. This article explores the history and impact of IASSIDD. In particular, it focuses on IASSIDD's role in the area of knowledge translation and promoting research to practice. The history of IASSIDD is documented. Its evolution is analyzed in the context of social, political, and scientific developments across the globe over the past 40 years. There has been an increased focus on evidence-based decision making and improving practice through research. There is evidence of a shifting emphasis from a primarily medicalized understanding of people with disability and their needs, to a focus that now includes the social, cultural, and economic needs of people with disability and their families. Greater attention is being paid to the construction of policy and service systems that are person-centered in their orientation, taking into account the priorities and aspirations of individuals, and emphasizing concepts such as inclusion, choice, and self-determination. Consistent with this, there is growing emphasis on inclusive research processes that value the cocreation of knowledge in partnership with people with disability and their families. IASSIDD and our disability research community need to discover and implement new methods of knowledge generation and translation. As an association that values research to practice, and improving the lives of people with disabilities, IASSIDD plays a major role in refining and promoting these emerging approaches to knowledge generation and translation, and their integration into policy and service developments.