Mental disorders are common, complex, highly morbid conditions for which basic underlying mechanisms are poorly understood. Despite the utility of many existing treatments, there remains vast unmet need for more effective and safer therapeutics. Most current medicines for mental disorders are based on chemical modifications of serendipitously discovered mid-twentieth-century prototypes, and widely used diagnostic manuals remain phenomenological and conceptually confused. After decades of stasis, research on mental disorders has reached an inflection point. Unbiased large-scale genetics provides information that, if interpreted circumspectly and integrated with neurobiology, provides “finding tools” for causal biological mechanisms that can advance discovery of biomarkers, preventive interventions, and better treatments. However, uncritically applied predictive genomic technologies can produce fatalism and exacerbate stigma. Moreover, polygenic risk scores for cognitive ability and risk of mental illness are already being offered commercially for embryo selection with in vitro fertilization, a worrisome resurgence of eugenics hiding in liberal (noncoercive) guise.