The number of Business Schools (BS) and their market share had increased in the last decades. Positioning strategy of BS is crucial in today's competitive and changing environments. Thus, paying attention to student's satisfaction and the factors, which motivate their selection, are relevant for service quality assurance in BS. This paper designs a scale to measure these perceptions as a useful tool for BS managers in the pursuit of excellence. Using a mixed analysis methodology, the most prominent dimensions detected in the literature were validated by BS managers and later by BS graduates. Internal and external dimensions compose the resulting scale, named BS-QUAL. The internal dimensions are related to Academic staff, Services, Facilities, and Sustainability while the external factors are related to Preparation for the future, Internationalization and Notoriety. BS-QUAL could be useful for the top management of BS to develop strategies that minimize the distance between student expectations and service provided.