Since the introduction of SERVQUAL as a measure of perceived service quality, questions have been raised regarding its validity, and competing scales have been developed. This paper reviews these debates and, in particular, compares the concept of expectations in service quality research with the concept of expectations in traditional satisfaction/dissatisfaction research, presenting the authors' perspective. Furthermore, this paper proposes a causal model of the relationships among expected performance, perceived performance, and service quality, based on the social judgment theory perspective that expected performance influences perceived performance. Within the framework of this model, propositions are established suggesting that perceived performance is either assimilated toward or contrasted against expected performance depending on consumers' knowledge level and involvement with the service. Finally, additional suggestions for future research in this area are provided.