Confidential informants have long occupied central role in the criminal investigation efforts of law enforcement authorities. Yet, there exists minimal contemporary scholarship to help illuminate the complex relationships and roles associated with covert intelligence gathering. This book draws upon a rich array of fieldwork and face-to-face interviews with police officers to provide insight into the confidential informant phenomenon. This concept of the police-citizen information exchange is set forth to account for the broad rubric of intelligence collection done by police. A four-part framework is provided to organize the exchange types based upon the motivations and goals that underlie the relationship. The utility of confidential informants is thoroughly explored, with attention focused on the potential benefits and pitfalls that follow. Detailed consideration is given to how officers recruit, nurture, and manage confidential informants. We argue that the police-citizen information exchange has become deeply woven into the fabric of contemporary policing, beginning with vice crime enforcement but emanating outward, so much so that scaling it back warrants a series of daunting practical considerations.