Studies of perceptual expertise typically ask whether the mechanisms underlying face recognition are domain specific or domain general. This debate has so dominated the literature that it has masked the more general usefulness of the expertise framework for studying the phenomenon of category specialization. Here we argue that the value of an expertise framework is not solely dependent on its relevance to face recognition. Beyond offering an alternative to domain-specific accounts of face specialization in terms of interactions between experience, task demands, and neural biases, expertise studies reveal principles of perceptual learning that apply to many different domains and forms of expertise. As such the expertise framework provides a unique window onto the functional plasticity of the mind and brain.