This thesis describes usability goals for method tools. Method tools are a type of CASE-tool aiming to support computer- and method-based information systems development. The aim of the thesis is to develop knowledge in order to suggest recommendations for achieving more usable method tools. The thesis takes an action perspective. An important starting-point in identifying usability goals are the existing modelling acts in the system development process specifying requirements for how method tools shall be developed.The thesis is performed as a prototyping approach embracing three steps. Output from a previous step is used as input to the following step. Further the thesis is based on studies of real cases where actors have interacted with method tools. In order to gain data I have used questionnaires, interviews and observations. The thesis embraces 12 usability goals for method tools. These goals are empirically generated and theoretically grounded. The identified usability goals are primary oriented towards the use situation system developer, method tool and task. Several usability goals can be characterised as more general and therefore are valid in areas beyond this use situation.The main contributions of this thesis are recommendations for developing method tools, a goal-means hierarchy presenting a composite description of usability attributes for method tools, characterising knowledge in a taxonomic form and a model which describes how modelling acts are related to usability goals.