Although industrial and product designers are keenly aware of the importance of design aesthetics, they make aesthetic design decisions largely on the basis of their intuitive judgments and "educated guesses". Whilst ergonomics and human factors researchers have made great contributions to the safety, productivity, ease-of-use, and comfort of human-machine-environment systems, aesthetics is largely ignored as a topic of systematic scientific research in human factors and ergonomics. This article discusses the need for incorporating the aesthetics dimension in ergonomics and proposes the establishment of a new scientific and engineering discipline that we can call "engineering aesthetics". This discipline addresses two major questions: How do we use engineering and scientific methods to study aesthetics concepts in general and design aesthetics in particular? How do we incorporate engineering and scientific methods in the aesthetic design and evaluation process? This article identifies two special features that distinguish aesthetic appraisal of products and system designs from aesthetic appreciation of art, and lays out a theoretical foundation as well as a dual-process research methodology for "engineering aesthetics". Sample applications of this methodology are also described.