The concept of conditioned reinforcement has received decreased attention in learning textbooks over the past decade, in part because of criticisms of its validity by major behavior theorists and in part because its explanatory function in a variety of different conditioning procedures has become uncertain. Critical data from the major procedures that have been used to investigate the concept (second-order schedules, chain schedules, concurrent chains, observing responses, delay-of-reinforcement procedures) are reviewed, along with the major issues of interpretation. Although the role played by conditioned reinforcement in some procedures remains unresolved, the results taken together leave little doubt that the underlying idea of conditioned value is a critical component of behavior theory that is necessary to explain many different types of data. Other processes (marking, bridging) may also operate to produce effects similar to those of conditioned reinforcement, but these clearly cannot explain the full domain of experimental effects ascribed to conditioned reinforcement and should be regarded as complements to the concept rather than theoretical competitors. Examples of practical and theoretical applications of the concept of conditioned reinforcement are also considered.