The purpose of this paper is to review likely and desirable developments for the rest of this century in the application of systems ideas to the general practice of the Craft of Investigation. I use that phrase, which was first developed by Majone (1984) to cover both the work of professional in-house investigators, such as Operational Research, and those of troubleshooting teams and ad hoc task forces which have some formal training on how to tackle ill-defined problems. The word Craft is thus used in its traditional sense as an activity which combines knowledge and understanding, experience and initiative. The emphasis will be on in-house investigation, but much of what is said will also apply to the work of consultants, although there are many subtle but fundamental differences in the work of external consultants and in-house teams which have yet to be adequately explored.