The results are given of a series of case studies conducted at different industrial sites in the framework of the ESF/EPSOM (Eureka Software Factory/European Platform for Software Maintenance) project. The approach taken in the case studies was to directly contact software maintainers and obtain their own view of their activity, mainly through the use of interactive methods based on group work. This approach is intended to complement statistical studies which can be found in the literature, by presenting the perspective of the maintainers based on their experience. The aim of these studies has been to gain a better understanding of maintenance needs and constraints, and to highlight directions which could lead to improvements in the quality and efficiency of maintenance activities. The results obtained tend to conform the main preoccupations of the maintenance community, with an emphasis on two types of needs which appear crucial in the domains of activity of the partners, namely: the transfer, preservation and maintenance of knowledge; and the mastering of the maintenance process