The built environment is shaped unselfconsciously and self-consciously by human actions and those of other species as well as the forces of nature. The focus in this chapter is on self-conscious design processes but, as a point of departure, the characteristics of the unselfconscious design process is described. Architects design objects and habitats self-consciously following a specific process. Few schools of architecture offer courses on design methodology or studios that explore different modes of thinking. Students unquestioningly internalize a model of the design process through their efforts in the design studio. This situation needs to change if architecture is to develop as a discipline. The knowledge base to form a declarative body of procedural theory is available, if far from complete. Distinctions can be made between problem-oriented and solution-oriented approaches to design. It is also possible to differentiate between depth-first and breadth-first approaches to idea generation. The chapter describes these approaches and their implications. Explanations are weaker because few researchers have been attracted to studying design processes. It is, nevertheless, possible to present a declarative procedural theory of design. This body of knowledge is teachable as Hebert Simon advocated in his book The Sciences of the Artificial. To better understand current design efforts our knowledge of the affordances of different configurations of the built environments and the building typologies on which architects often base their designs needs to be clarified.