We construct tools for measuring psychological characteristics, cognitive abilities, knowledge and other human traits. We participate in developing original Czech tools, as well as in localizing international methods for a Czech context. We use a wide array of psychometric models to check the functionality of research psychodiagnostic tools and tests. We investigate the details of the process of responding to a range of testing items, which are the foundation of methodological construction, and also the use of methods by professionals in specialized areas of psychological practice.