The intention of tailorable systems is to make it possible for end users to evolve an application to better fit altered requirements and tasks, and to make the system more endurable. This thesis discusses tailorable systems in the context of a rapidly changing business environment. The objective was to determine what is necessary for a tailorable business system to continuously adapt to expanding requirements and thereby live up to the intention of the system. The thesis includes five different studies, of which one is a literature study. The other four studies were conducted in three projects; one technical project exploring the possibility to use Metaobject Protocol in tailorable systems, one project in an explorative environment concerned with physical interfaces and one project, that also embraced user participation and user evaluation, regarded the possibility for end users to manage system infrastructure. The projects began with field studies (including participant observations and interviews) and workshops with users and developers. In each project, based on the outcome, an end-user tailorable prototype was developed. The prototypes were used for evaluating possibilities and problems with tailorable systems. Taken together the evaluations revealed what was required to make a tailorable system work as intended in a rapidly changing business environment. It could be concluded that tailoring is a good way to evolve a system to meet altered needs, because people who already possess the required domain knowledge can make changes quickly. Tailoring is not however enough, because the tailoring capabilities are always limited, meaning that tailoring cannot support completely unanticipated changes. In such cases the tailoring capabilities must be extended. Since such changes are only concerned with the system itself, and not the business task, it is hard to motivate even skilled users to make these types of changes. Tailoring activities must therefore be coordinated with software evolution activities performed by professional developers. This allows the system to adapt continuously to a rapidly changing business environment and thereby live up to the intention of the system. The final conclusion is that there is a need for close collaboration between end users, tailors and developers to make tailorable information systems adaptable to rapid changes in the business environment as well as being endurable. The collaboration has to be supported in the structure of the system by providing support for the work of users, tailors and developers.