When people are facing difficulties, they often feel the need for a confidant—a person to vent to or talk things through with who will offer sympathy or understanding. How do they decide on whom to rely? In theory, the answer seems obvious: if the matter is personal, they will turn to a spouse, a family member, or someone otherwise close. In practice, what people actually do often belies these expectations. This book follows a group of graduate students as they cope with the stress of their first year in their programs, probing how they choose confidants over the course of their everyday experiences and unraveling the implications of the process. The book then tests its explanations against data on national populations. It shows that rather than consistently rely on their “strong ties,” people often take pains to avoid close friends and family, because these are too fraught with complex expectations. People often confide in “weak ties,” as their fear that their trust could be misplaced is overcome by their need for one who understands. In fact, people may find themselves confiding in acquaintances and even strangers unexpectedly, without much reflection on the consequences. Amid a growing wave of big data and large-scale network analysis, the book returns to the basic questions of who we connect with, how, and why, and upends decades of conventional wisdom on how we should think about and analyze social networks.