Results of a primary meta-analysis indicated a significant main effect o the organizational behavior modification (O.B. Mod.) approach on task performance (d. = .51; a 17 percent increase) and a significant treat ment-by-study interaction. To account for within-group heterogeneit of effect sizes, we conducted a two-level theory-driven moderator analysis by partitioning the sample of studies first into manufacturing and service groups and then into seven classes of reinforcement inter ventions. Results indicated a stronger average effect of O.B. Mod. in manufacturing organizations, moderation by the type of contingent interventions, and "pairwise" differences among average effect sizes in both organizational types. The practical implications of these findings for solving the challenge of improving performance without adding cos are discussed.Although the operant theoretical foundation for the application of b havioral analysis or behavior modification was established in the 1 (Rogers & Skinner, 1956;Skinner, 1953), it has only been within the las years that the basic reinforcement paradigm has been introduced to the s of organizational behavior and applied to human resource managem (HRM) (Adam & Scott, 1971;Luthans & White, 1971;Nord, 1969). Am several application models proposed within this conceptual framework (e Brethower, 1972;Gilbert, 1978;Komaki, 1986;Miller, 1978;Scott & Podsakoff, 1985), the organizational behavior modification (O.B. Mod.) model, first presented by Luthans (1973) and fully developed by Luthans and Kreitner (1975Kreitner ( , 1985, has received considerable attention from both organizational behavior researchers (e.g., Andrasik, Heimberg, & McNamara, 1981; Frederiksen, 1982aFrederiksen, , 1982bFrederiksen & Johnson, 1981;O'Hara, Johnson, & Beehr, 1985) and HRM practitioners (cf. Andrasik, McNamara, & Edlund, 1981;Frederiksen & Lovett, 1980). Based on the conceptual premises of classical behaviorism (Pavlov, 1927;Watson, 1913), reinforcement theory (Ferster & Skinner, 1957;Skinner, 1938Skinner, , 1966Skinner, , 1969, and the principles and techniques of applied behavioral analysis or behavior modification (Bandura, 1969;Ferster & Perrott, 1968;Kazdin, 1975;Wenrich, 1970), the O.B. Mod. model represents a behavioral approach to the management of human resources in organizational 1122 Published by Academy of Management. Used by permission. Stajkovic and Luthans 1123 settings. Specifically, the model provides a five-step application framew for identifying, measuring, analyzing, contingently intervening in evaluating employees' task-related behaviors aimed at performance provement (Luthans & Kreitner, 1975. Figure 1 Development of the O.B. Mod. model has generated a number of studies that have tested its effectiveness in a wide range of manufacturing, service, and not-for-profit organizations and in Western and other cultures (e.g., Welsh, Luthans, & Sommer, 1993b). The application of the O.B. Mod. approach has been shown to positively affect manufacturing productivity (e.g., Welsh ...