In this paper, we investigate cell formation problems in a manufacturing system with flexible processing and routeing capabilities. Flexible processing means that a part can be manufactured by any one of several process combinations. Flexible routeing means that even when the processes are fixed, the part can traverse any one of several routes—each offering the same processes. The cell formation problems for these types of manufacturing systems are different from traditional problems. Traditional cell formation problems are for manufacturing systems with fixed processes and routes where one knows what machines will be used for manufacturing the parts. However, this information will not be available in the flexible systems discussed here, since a part can be completed by any one of the many different combinations of machines. In other words, it is possible to manufacture two identical parts using different sets of machines. Traditional cell formation techniques rely on knowing the specific machine usage information of parts, therefore cannot be applied to the cell formation problems defined here. We propose a solution procedure that can overcome this difficulty and allow us to solve the cell forming problems in this flexible processing and routeing manufacturing environment.