Design means conceiving of objects or processes for accomplishing goals and it is a way to intentionally changing part of the world, as it is the case in prospective ergonomics. The design process usually requires creativity since designers have to propose objects or processes that are both new/novel - and possibly unexpected - and adapted to the design situation (e.g., useful and usable by future end-users). The goals of a particular design task and the intended functions of the design to be produced are not fully available at the outset. Thus, part of designing consists in constructing those goals and functions. It occurs as designing proceeds and it has the potential to alter what has been decided before, which makes designing non-monotonic across time. The cognitive processes and mechanisms involved in the creative design activities are of particular interest and are described in this entry as well as potential ways to favour creative design.