This chapter focuses on the use of design guidance as a tool in the design/development process. It begins with a short introduction to design guidance as a generic type, revealing its variety and distinguishing characteristics. Based on empirical research in England derived from a national pilot program, the chapter goes on to examine one particular form of guidance – the design code. The aim here is to explore in greater depth the relationship between design guidance and the broader design and development process. The discussion recognizes that the nature and limitations of all forms of design guidance need to be fully understood before they are applied in practice.