Design provisions for deflection control of concrete structures are generally empirical in nature and based on previous experience. Due to the increasing use of high strength materials, longer spans, and as a result more flexible members, a more rational approach is desirable. This paper explores the applicability of the utility theory as a basis for developing deflection control criteria. The approach considers uncertainties in member behavior and loading as well as lack of well-defined discrete serviceability limits. Monte Carlo simulation is used to develop histograms of selected deflection parameters. A serviceability loss function is then specified to define the onset of serviceability failure and an upper limit representing complete serviceability failure with associated costs. Optimum structural parameter (member depth) is obtained by minimizing total cost consisting of initial construction cost and probabilistic cost of failure. Results for one-way slabs are developed and compared with current ACI code provisions for minimum thickness.