ABSTRACT
The approach to assess library performance was approbated;the results are discussed. The proposed instruments enable to calculate several indicators of social, technological, economic and organizational efficiency as well as summary efficiency index. This method enables to define whether the library goals are achieved, to relate the results to invested resources, to evaluate process satisfaction degree. The authors suggest alternative indicators for normal and extreme circumstances (e. g. during COVID-19 pandemic). The assessment is based on the indicators included into 6-NK statistical standard (Public Library Report) as well as the indicators used in plans, reports, analytical reviews to be submitted to founders, central libraries, or regional authorities. The methods require no extra information or special research. Its stage-by-stage description makes them replicable, which is evidenced by approbation results presented by many libraries. The element index enables to measure the indicators, to analyze and compare them, and to make informed managerial, strategic and political decisions. The universal method can be applied irrespective of library type, status, and departmental subordination.