The article elucidates the conception of “Concise Ukrainian-Polish dictionary of set expressions: lexical equivalents, phraseologisms, proverbs and sayings” which implements an international Polish-Ukrainian project. The Council of Europe is known to devote much attention to the problems of the development of languages, their improvement and, correspondingly, to the development of linguistics, in particular, its applied branch, which includes lexicography. The dictionary under analysis represents: 1) the status of set expressions which, being widespread in the examined lingual cultures, reflect the mentality of the nation, its history, national specificity etc., 2) principles and procedures of semantic transformations of set stable lingual units by means of the cognate Slavonic language. The conception of the Ukrainian-Polish phraseological dictionary has been realized in the history of Ukrainian and Polish phraseography for the first time. The conception is based on 1) the detailed analysis of the theoretical and practical experience of compiling dictionary of this type; b) thorough outline of the system of headwords with the heterogeneous status of: 1) the representation of the mentality of the nation, its ethnographic features., norms of etiquette, ethics, psychology, theme (ideographic aspect) etc.; 2) structure, semantics and pragmatics; 3) specificity of functions and style. The conception of the dictionary is based on the methodological foundation of anthropocentrism and main phraseographic principles of bilingual dictionaries aiming at the most adequate representation of a corresponding lingual units by means of another language. The dictionary will contribute to the further research in the sphere of contrastive Ukrainian- -Polish linguistics and phraseograpical theory.