In 2003, Lidwell, Holden and Butler published a well-documented collection of 100 universal principles of design. Among these are 28 principles explaining 'How can I increase the appeal of a design?' These principles, laws, or guidelines deal with the Golden Ratio, similarity, savannah preference, symmetry and color; principles that will also appear in this chapter. Most of these principles have for centuries been applied in the arts, and have over the last century been uncovered and tested in psychological experiments. The authors claim that the application of such principles increases the probability that a design will be successful' (Lidwell et aI., 2003, p. 11). We are tempted to adopt this claim, but want to take it a little further. Understanding why people are aesthetically attracted to some properties or patterns over others will support designers to make founded decisions on the attractiveness of their design. Over the past ten years, the first author has given many lectures on visual aesthetics to students of industrial design. The main message of these lectures always was: People may and do differ extensively in their aesthetic reactions to objects; these reactions as well as the differences are not arbitrary, but lawful. Contrary to what the popular expression 'de gustibus non est disputandum' holds, there is accounting for taste! Does this mean we can (already ) explain all varieties in aesthetic preference? Of course we cannot. There are still many unresolved issues and unpredicted (but not unpredictable) exceptions . But, after more than 100 years of theorizing and experimentation, we have come to understand quite a bit about the drivers of people's aesthetic responses to the things around us in general and designed artifacts in particular. This chapter aims to bring together these insights.