The word “design” is most frequently employed to refer to the action of planning and making (designing something), and to describe the end result or artifact of this action (a design). Designers often refer to their activity as problem-solving and view their work as a response to opportunities and needs in the market identified by corporations, entrepreneurs, consumers, governments, and nonprofit organizations. Design practice tackles problems that can range from the creation of such small things as business cards to the planning of entire urban systems. Horst Rittel argues that the problems design handles are wicked (as well as incorrigible and ill-behaved) and new methodologies are required to tame them. The sheer wickedness and complexity of these issues warrants engagement with other disciplines. This chapter suggests that transdisciplinarity is one of the most promising strategies for dealing with and taming the wicked, ill-behaved, and incorrigible problems of design.