A little-noticed but nonetheless profound evolution in medical practice took place in the latter half of the 20th century. Until that time, individuals visited their physicians only when they experienced symptoms and worried they were ill. Now they began to visit their physicians to undergo testing to detect occult disease, even if they felt healthy and were asymptomatic. A new mantra worked its way into medicine in the United States and was quickly adopted by the public: get tested, diagnose disease early, and be treated while the problem is “small” before it becomes “big” or, even better, before a potential disease becomes a reality. This was, and still is, the right thing to do—correct? Well, maybe not, claim Dartmouth researcher-physicians H. Gilbert Welch, Lisa Schwartz, and Steven Woloshin. Such testing of healthy individuals all too often results in overdiagnosis and overtreatment, because in reality there is “nothing to fix.” As a result, contend the authors, although a few will be helped, many will be overdiagnosed, and some will be harmed. This theme permeates the book.