Human factors research in conceptual modeling is scarce. Recently, quality assurance frameworks, methods and tools for conceptual schemas have received increased research attention, but the perception of quality by schema users has largely been ignored in this stream of research. This paper proposes a tentative model of user beliefs and attitudes towards the quality of conceptual schemas. The proposed model is original in the sense that it includes both perceived semantic quality and perceived pragmatic quality measures. The paper also presents a new measurement instrument for the perceived semantic quality of conceptual schemas. This instrument was used in a classroom experiment that tested the proposed user beliefs and attitudes model. It was shown that the perceived semantic quality of a schema is directly related to its perceived usefulness and perceived ease of use and indirectly to the user satisfaction with the schema.