The authors determine the utility of applying two display design principles toward the development of interfaces for engineering design. The first principle, called the Proximity Compatibility Principle, specifies that displays relevant to a common task or mental operation should be rendered close together in perceptual space. The second principle, called the Control-Display Compatibility Principle, stipulates that the spatial arrangement and manipulation of controls should be easily distinguishable. To examine the utility of both principles, the authors conducted an experiment comparing the ability of subjects to find effective designs using a separable versus a configural interface in a multi-objective engineering design task. Results suggest that the proximity compatibility principle is an effective indicator of task performance. Moreover, the control-display compatibility principle can be used as an indicator of performance efficiency. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 61–81, 2006.