Cumps, Bjorn2017-12-022017-12-022013http://hdl.handle.net/20.500.12127/4760Control offers a critical differentiator between successful and failed interfirm service exchanges. The application of informal control to improve supplier performance has been well established, but the effect of formal control appears profoundly equivocal. This study proposes that the actual effect of formal control depends on its mode (output vs. behavior) and its relationship with the service type (mass vs. professional) and informal control. With survey data from 252 service buying organizations, the results indicate that output control interacts with service type to determine perceived supplier performance (PSP). Buyers’ reliance on high output control has a positive effect on PSP in mass service exchanges, this effect becomes negative in professional service exchanges. The effect of the interaction of behavior control and service type also depends on the presence of informal control. Buyers’ reliance on high behavior control exerts a more positive effect on PSP in professional service exchanges than in mass service exchanges, but only in the presence of informal control. These findings have key implications for both theory and practice.enOperations & Supply Chain ManagementGlobal Banking and Finance Review652685665