This book presents a comprehensive survey of perceptual expertise in visual object recognition, and introduces a novel collaborative model, codified as the "Perceptual Expertise Network" (PEN). This unique group effort is focused on delineating the domain-general principles of high-level visual learning that can account for how different object categories are processed and come to be associated with spatially localized activity in the primate brain. PEN's approach brings together different traditions and techniques to address questions such as how expertise develops, whether there are different kinds of experts, whether some disorders such as autism or prosopagnosia can be understood as a lack or loss of expertise, and how conceptual and perceptual information interact when experts recognize and categorize objects. The research and results that have been generated by these questions are presented here, along with a variety of other questions, background information, and extant issues that have emerged from recent studies, making this book a complete overview on the topic.