Understanding and supporting conceptual model design is an important issue in Model Management System (MMS) research . While there are a broad range of aspects which af fect conceptual design , this study focuses on the use and the support of abstraction in the design process . We classify the use of abstraction in design into three categories : vertical , horizontal and general abstraction techniques . We then propose a theoretical framework which suggests the completeness of the design , the development of higher level concepts in design , and the design organization as the three dimensions of design output that can be enhanced by ef fective use of these abstraction techniques . The proposed framework was empirically tested on a design problem using non-domain experts , with a software prototype that provided abstraction aids . The findings indicated significant ef fects of abstraction aids on the three dimensions of design output . Specifically , training exercises with comprehensive examples of various design strategies significantly improved both the number of high level ideas generated and the design organization compared to unaided designs . The completeness of designs was enhanced by both the design environment structure and the examples and analogies provided during training . The implications of this study are : (a) it is possible to measure the impact of abstraction support on the conceptual design process , (b) the proposed measures can be used in the development and evaluation of design support systems , and (c) abstraction support can significantly improve the quality of design by non-domain experts .