||The quality of performed functions is crucially important in the process of use of interactive Internet maps. Functionality determines and describes the capabilities provided to the user: e.g., viewing, analysis or integral management of map elements. The dissertation presents original methodology that allows for integral quantitative evaluation the quality of implementation of functions of Internet maps of various types and complexity. The users‘ needs are taken into account. The methodology is based on the results of three investigations: user experiences, expert opinions and actual functions of existing interactive maps. All these aspects are combined into one complex, cumulative and flexible system of criteria and indices for qualimetric assessment of quality of implemented map functions. Original Internet based CartoUI software (www.cartoui.com) has been developed for practical implementation and verification of this methodology. The software also provides tools for analysis of information collected during particular research or for selected time span. CartoUI is available for everyone to use it for investigation into functionality of interactive Internet maps and for analysis of users‘ needs. The dissertation also provides detailed practical recommendations for development of diverse interactive internet maps tailored for different user groups. The recommendations are based on research on particular users‘ needs clarified by means of CartoUI.