The OSA is a client-centered self-assessment tool suitable for a wide range of clients. The assessment is conducted using a simple paper-and-pencil test, where the client marks how well they master individual areas and how important these areas are to them. Following this, they choose the areas to focus on during therapy. The manual provides a detailed description of both the application and the fundamental principles of the underlying occupational therapy model (the Model of Human Occupation (MOHO)). It also discusses the possibility of using the data for scientific purposes. In addition to the assessment forms, the manual includes templates for treatment planning and follow-up assessments. All templates can be used as photocopying templates.