Remarkable progress in eye-tracking technologies opened the way to design novel attention-based intelligent user interfaces, and highlighted the importance of better understanding of eye-gaze in human-computer interaction and human-human communication. For instance, a user's focus of attention is useful in interpreting the user's intentions, their understanding of the conversation, and their attitude towards the conversation. In human face-to-face communication, eye gaze plays an important role in floor management, grounding, and engagement in conversation. Eye Gaze in Intelligent User Interfaces draws on ideas from a number of contributors working on how attentional information can be applied to novel intelligent interfaces. Part I focuses on analyzing human eye gaze behaviors to reveal characteristics of human communication and cognition; Part II addresses estimation and prediction of the cognitive state of the users using gaze information; and Part III presents proposals of novel gaze-aware interfaces which integrate eye-trackers as a system component. The contributions highlight a direction for the future of human-computer interaction, and discuss issues in human attentional behaviors and face-to-face communication which are essential in designing gaze aware interactive interfaces.