The game of tennis, for many years somewhat neglected by sport historians, has recently become the focus of greater attention among academics. Its global importance has been significantly underlined in the forty-five wide-ranging chapters contained in the 2019 Routledge Handbook of Tennis: History, Culture and Politics. One of the leading themes in the developing literature on tennis has been the complex, fluctuating relationship between amateurs and professionals. In the early years of lawn tennis during the late nineteenth century, with the game spreading rapidly across large parts of the world, the amateur notion that it should be enjoyed for itself and not for financial reward developed a powerful hold. The tenacious grip of amateur administrators was gradually eroded during the twentieth century, both by the rise of stand-apart professional tours and by the spread of illicit payments and inducements to top amateurs in contravention of the international rulebook. But it was only after the arrival of the “open era” in 1968 that professionalism took root and shifted the sport inexorably toward the multimillion-dollar enterprise it has become today. Independent scholar Greg Ruth makes a welcome contribution to our understanding of this key feature of tennis history by providing, for the first time, a comprehensive overview of the central part played in the unfolding amateur-professional story by the United States, which alongside Britain, France, and Australia, acted as one of the traditional “big four” powerhouses of world tennis.The author employs a broadly familiar threefold periodization structure to contextualize the shift from amateurism to professionalism. In the first stage, from the origins of lawn tennis in Britain in the 1870s through to the mid-1920s, national associations around the world that codified tennis and determined its ethos—including in the USA—were resolutely amateur in outlook. A new phase opened up, according to Ruth, with the emergence in the mid-1920s of the first professional tours in North America, spreading episodically thereafter to other parts of the world. These short-lived tours were pioneered by celebrity stars such as Suzanne Lenglen and Bill Tilden, who abandoned amateur ranks in order to receive above-board remuneration for their endeavors. Tennis thereafter became a sport divided against itself, with anyone turning professional barred from competing at top amateur events, including the prestigious French, Wimbledon, and US Championships. Tensions between traditionalist amateur administrators who dominated the national associations and players and promoters participating in pro tours were only resolved after top events were made open to amateurs and professionals alike in 1968, ushering in the third, ongoing stage in the evolution of the sport.Within this chronological framework, the author's major insights are found in a series of well-formulated chapters—all based on admirably extensive primary and secondary source research—that bring together the interaction between individual players and promoters and between social, geographic, and economic changes, which all impacted the American contribution to the transformation of elite-level tennis. For example, there are illuminating contrasts between the stricter amateur heartlands of the Atlantic Coast and the inexorable rise to prominence of West Coast tennis, such as that of Southern California, which the writer notes “developed the most robust player development program in the world, thanks in no small part to monetizing the amateur game” (45). As well as showcasing the influential role of both men and women (with astute profiles of the likes of Jack Kramer, Pancho Gonzales, Gladys Heldman, and Billie Jean King), subsequent chapters highlight the pivotal part played in shaping open tennis by promoter bodies such as World Championship Tennis, sports agencies, and above all Mark McCormack's International Management Group.Aside from a minor quibble about the choice of a French player for the front cover illustration, given the book's title and central spotlight on American tennis, the only place where this reviewer felt the analytical lens might have been widened comes in the conclusion. Greg Ruth ends by extending his post-1968 narrative to show how the fluid tournament structures of the early open era evolved into the pattern—overseen by the ATP and the WTA for men and women, respectively—that remains familiar today. As the transition from amateurism to professionalism was such a convoluted, uneven process, some consideration of wider questions of historical causation and consequence might have been beneficial here. How should America's role in the move to open tennis be viewed in relation to that of other leading tennis nations, the British, French, and Australians? Was the status quo ultimately overturned as the inevitable consequence of growing commercialism and looser social hierarchies, or was it more the result of short-term contingent factors, suggesting amateurism might have survived to at least fight another day beyond 1968? It's a testimony to advances in tennis scholarship, to which Greg Ruth's book acts as a valuable new addition, that these broader issues can now be more systematically addressed.