Three enterprises have been diagnosed and analysed according to a change methodology, especially developed to identify and structure the needs for improvement of information handling and production planning. The results confirm that planning and information handling were difficult problems to manage in the studied SMEs. However, behind this statement lie entirely different problems in different enterprises. This put special demands on a change approach to be appropriate. A number of criteria for a change methodology are listed. The most important are a high face validity for different employees, a high credibility of the identified hypothetical cause – effect relationships, an ability to guide changes, a possibility to handle both details, systems and their relationship, an unbiased approach to the initial problem description and ability to handle and play down threatening or taboo questions.