This training manual is designed to prepare behavior assistants to teach parents and other family members how to use operant conditioning techniques to solve family problems with children. Readers are warned not to attempt to put the recommended procedures to actual use until the text is fully comprehended. Chapter I gives arguments to justify the use of operant conditioning techniques within the family setting. Vicious and positive cycles of interactive events are described and punitiveness is distinguished from operant mediation. Chapter II details basic principles of operant mediation. The core concepts of operant conditioning are described and illustrated in non-technical language. Chapter III sequentially outlines and discusses elements of the mediation process. Referral behaviors are distinguished from focal behaviors. Mediator tasks include observing the focal person and the occurrence of focal behavior, keeping records, dispensing tokens, delivering back-up reinforcers, and evaluating the mediation. Further dimensions of the mediation such as selecting the in-family mediators, maintaining the difference between operant mediation and contractual management, and setting up the token system and the menu of back-up rewards, are discussed. In Chapter IV various parent arguments against the use of operant mediation are analyzed and solutions to parental objections are suggested. (RH)