One of the most exciting places for psychologists to practice is in health care settings. This excitement comes about as health care is increasingly a context that prompts innovation in practice and policy development. One of the most compelling arguments for psychological practice in health care settings is the growing emphasis nationally on the integration of psychology into primary care. As described by Gray, Brody, and Johnson (2005), primary care is "behavioral health management." Thus, a comprehensive system with psychologists who are equal partners in a multidisciplinary health care team has been recognized as a reform that can meet the critical goals of health care cost containment as well as demonstrate improved patient outcomes. In fact, James and Folen (2005) described primary care as psychology's "next frontier."Psychologists are not new arrivals to the health care setting. Belar and Deardorff (2009) traced the development of clinical health psychology back to the 1970s: They noted that psychologists initially were involved primarily as researchers, investigating psychological predictors or sequelae of medical disorders. With regard to psychological practice, early concerns centered on how psychology, as a discipline concerned with mental health, related to disorders of physical health. (For a review of the interaction of organized psychology with the Joint Commission on Accreditation of Hospitals, see Zaro, Batchelor, Ginsberg, & Pallak, 1982.) Also, psychology's longstanding adherence to a mind-body dualism that locates client issues in either the physical or mental domain, with no intersection of these domains, worked against psychologists obtaining a practice role in health care. However, the contributions of clinical health psychologists in research and in practice were undeniable; and the domains of assessment, intervention, and consultation have continued to develop. The focus of this chapter is on the domain of assessment, primarily as it relates to medical patients.This chapter begins with a brief discussion of formal aspects of health care settings and introduces the reader to challenges in medical care. Because the medical setting is the context for assessment and the medical patient is the client for assessment, the setting itself must be understood as a critical influence on the practice of psychological assessment. The reader is then introduced to the most typical assessments used in medical settings. The chapter also discusses new directions in assessment. For many patients, medical advances have resulted in the patient's surviving what would previously have been a fatal accident, event, disease, or condition. In this case, the diagnosis becomes one of chronic illness, and the patient's return to work (or normal life) is of interest. Last, because growth of prescription privileges will certainly influence assessment practices in medical settings, the influence of this shift in psychological practice is considered.The chapter concludes with an overview of ethical and legal issues inheren...