The term 'preclinical Alzheimer disease (AD) treatment' refers to interventions that are initiated in cognitively unimpaired at-risk individuals, and are intended to postpone, reduce the risk of, or prevent the clinical onset of AD. In this article, the authors review emerging strategies for the accelerated evaluation of preclinical AD treatments, and discuss the work that has set the stage for implementing these strategies. In particular, they highlight the role of the Collaboration for Alzheimer's Prevention (CAP)—an initiative that is designed to help stakeholders advance AD prevention research in a coordinated, transparent and effective way.