Medically unexplained symptoms are the defining feature of somatoform disorders (SFD) as currently included in Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and the International Classification of Diseases, Tenth Edition. Cognitive, behavioral, biological, and social variables are important to our understanding of SFD. Research in the past decade has highlighted the central role of (a) prolonged attention allocation to bodily sensations, (b) the dysfunctional role of catastrophizing symptoms as signs of severe illness, (c) neuroendocrine alterations, and (d) the influence of illness behavior (e.g., the avoidance of physical activity) on the maintenance and chronicity of SFD. Additionally, conditioning approaches have demonstrated that perceiving somatic discomfort can easily be learned. In addition to current models of etiology and pathogenesis, the existing evidence on the efficacy and effectiveness of psychotherapy for SFD is reviewed. Finally, future directions and some current blind spots in research on SFD are outlined.