When developing software and increasing the number of its features, supporting the users’ most important goals efficiently in the user interface is a challenge. On the other hand, users’ goals can also change gradually, partly even because of the software itself. For these reasons, the user interface occasionally needs to be re-evaluated as a whole, and then redesigned based on users’ needs. A particular challenge to user interface design in business process modelling is creating process understanding. Process models include an abundance of detailed information that has to be communicated to the users in a clear and illustrative manner, so that the process can be improved.

In this thesis, the above-mentioned challenges were met by using a goal-based approach to developing the user interface of a business process modelling tool. The objective was to improve problematic user interface designs, and in addition, address two specific user interface problems: lack of visualisation of process data, and lack of support for modelling causal relationships and the time dimension.

To support the most important users’ goals in the user interface, three methods were used to discover the goals: user observations, interviews and simulation games. The emphasis was on knowledge-intensive processes, exemplified by the case processes from pilot companies. The goals were listed and prioritised with respect to five typical user profiles.

The new interface designs are presented as draft drawings that describe the user’s interaction with the software. The central improvements of the new designs are replacing dialog boxes with direct manipulation, dynamic editing of the model, showing the overview of the process, and visualising process data directly on the process chart. The new designs support most of the users’ goals in a more straightforward manner than the old interface.