Abstract To the clinician, alcoholism can appear as an amorphous entity that is confusing with respect to diagnosis, treatment prognosis, and the role of the health professional, despite its high incidence and associated morbidities and mortality when unrecognized or untreated. This chapter focuses on the clinical application of current knowledge, with the aim of being useful to the practitioner in working directly with patients for whom alcoholism may or may not be an already identified problem. It briefly reviews large-scale studies and then focuses on diagnosis and prognosis assessment and decision making. Also considered are current controversies in nomenclature and the chapter ends with an economic perspective with respect to healthcare and cost to society. As the introductory chapter, the goal is to provide a context of the scope of alcoholism and attendant problems for the rest of the chapters.