Usability inspection methods of user interaction designs have gained importance as an alternative to traditional laboratory-based testing methods because of their cost-effectiveness. However, methods like the heuristic evaluation are ad-hoc, lacking a theoretical foundation. Other, more formal approaches like the cognitive walkthrough are tedious to perform and operate at a high-level, making it difficult to sub-classify problems. This research involves the development and formative evaluation of the Usability Problem Inspection tool — a cost-effective, structured, flexible usability inspection tool that uses the User Action Framework as an underlying knowledge base. This tool offers focused inspections guided by a particular task or a combination of tasks. It is also possible to limit the scope of inspection by applying filters or abstracting lower level details. / Master of Science