The Amphetamine Years is a history of psychostimulant drugs and their clinical applications in post-World War II American medicine. Comprising such well-known substances as the amphetamines (Benzedrine, Dexedrine), methylphenidate (Ritalin), and phenmetrazine (Preludin), this class of pharmaceuticals has been among the most widely consumed in the past half-century. Their therapeutic uses for a variety of indications such as depression, obesity, and attention-deficit/hyperactivity disorder (ADHD) in children, not to mention their relevance for a number of different medical specialties, reveals that psychostimulants have occupied an important, if underappreciated role in the practice of modern medicine. In this dissertation, I illuminate the various ways in which physicians, particularly psychiatrists, put these drugs to work in clinical practice. In short, I contend that physicians exploited the wide range of physiological and psychological effects of psychostimulants and made a place for them in different therapeutic settings, even ones characterized by competing views and theories about the workings of the human body and mind. My dissertation is distinguished by two prominent themes. First, I emphasize the clinician perspective as a vehicle for understanding the history of the psychostimulants, as well as related developments in psychiatry, pharmacotherapy, and the political economy of drugs, in the second half of the twentieth century. Scholars such Nicolas Rasmussen, David Courtwright, and Ilina Singh have elucidated the history of psychostimulants by emphasizing how pharmaceutical companies positioned their products in the medical marketplace. My dissertation takes a different, yet complimentary approach by studying clinicians, themselves, to further historical comprehension of the place of these pharmaceuticals within postwar medicine, society, and culture. Second, I advance the concept of "therapeutic versatility" to explain their historical trajectories. The complex set of psychological and physical effects these drugs produced made them ideal for a diverse range of therapeutic applications, which explains why they were embraced by many different medical specialties, why they were marketed by manufacturers for a variety of indications, and why they have enjoyed an enduring therapeutic lifespan, in spite of increasing efforts since the mid-1960s to regulate their availability and control their consumption. In addition to these two overarching themes, I advance five specific arguments in my dissertation. First, I contend that pharmaceutical markets were simultaneously created by the drug industry and clinicians. Pharmaceutical firms' efforts to develop markets for their products have been well documented by historians, but in my dissertation, I underscore the role also played by clinicians in discerning drugs' applications. Second, I argue that twentieth-century psychiatry's conception of illness and therapeutics may not be served best by strictly dividing its history along lines of institutional and outpatient treatment. Third, I demonstrate how the use of psychostimulants by analytically oriented psychiatrists during the 1950s complicates historical notions of paradigm shift from a psychodynamic to biological orientation. Psychotherapy and psychopharmacology were not competing paradigms; in practice, doctors often employed both. Fourth, I assert that an appreciation of psychiatrists' empirical and eclectic approaches to the use of drugs is necessary to comprehend the rise of psychiatric pharmacotherapy in the postwar era. Finally, I contend that in order to understand the relationship between medical applications of psychostimulants and their extramedical consumption, it is necessary to conceive of a plurality of distinct "amphetamine cultures," each characterized by a unique set of relationships between physician-prescribers, patient-consumers, pharmaceutical firms, and political authorities.