The recent sequencing of the human genome has raised expectations that the identification of susceptibility genes for the major psychiatric disorders should soon follow. However, as detailed in Chapters 6 and 7, the complex genetic architecture of mental illness is likely to pose a continuing challenge to traditional linkage and association approaches. The expansion of functional brain imaging into the realm of psychiatric genetics has come at an opportune time. Two developments in functional brain imaging are likely to transform the role of brain imaging in psychiatric neuroscience and research—the failure of functional brain imaging to produce diagnostically specific measurements of illness vs the technical advances in magnetic resonance imaging (MRI) techniques. However, although the methodological details are growing ever more complex and appear unfamiliar, this dialectic between the psychiatric neuroscientists and the psychiatric clinicians is a familiar one. As was the case two decades ago when the debate centered on the relevance of structural brain imaging findings to the genetic causes of mental illness, the current quest for candidate functional brain imaging phenotypes should benefit all, since ultimately both clinician and neuroscientist seek to bridge the gap between brain mapping “findings” and neuronal pathology.