Intelligent adaptive systems (IASs) represent a significant technological advancement at the intersection of human factors and human-computer interaction, emphasizing the dynamic relationship between intelligent user interfaces and adaptive automation technologies. These systems are characterized by their ability to dynamically adapt to the context of user interaction and to be responsive to the operator’s characteristics, as well as cognitive and emotional states. This chapter provides a comprehensive overview of IASs, exploring fundamental technologies and adaptation approaches, such as rule-based, model-based, ontology-based, context-aware, and behavior-based adaptation. Moreover, the chapter highlights emerging issues associated with the integration of artificial intelligence (AI) technologies into contemporary adaptive systems. Additionally, it explores the design of IASs through a human-centered AI perspective, emphasizing the need for systems that prioritize user and societal well-being. Under this perspective, essential qualities that must be adhered to are presented, and ethical considerations that must be addressed to ensure transparency, fairness, and user trust in adaptive technologies are discussed.