The Adult Changes in Thought (ACT) Study is a complex, multifaceted research program, and the ACT Data Repository, built over 30 years, is a vital national data resource. Data and resource sharing are an important part of our research program. Given the complexity and variety of data sources, collaborators are encouraged to familiarize themselves with the descriptions of our various data resources and associated processes for collaboration. A description of the ACT cohort, including eligibility criteria and follow-up procedures, is also available in this section.