The topic of this graduate thesis is the Miroslav Krleža Lexicographic Institute. The Miroslav Krleža Lexicographic Institute was founded in 1950, it is a scientific institution for encyclopedic and lexicographic activities. This paper will write about the history of the only Croatian institution that has been systematically engaged in lexicography for seventy years. The history of the institute will be written about from the founding to the present day and will describe all the changes that have occurred in the institute as well as how it got the name it bears today. The founder and creator of the institute is the Croatian writer and lexicographer Miroslav Krleža, so one part of the work will be dedicated to him and his work related to the work of the lexicographic institute. In addition to the history of the institute, lexicographic and encyclopedic activities will be written about, including the collection and processing of data of lexicographic units and the design and production of encyclopedic and lexicographic units. As an experimental part of the graduate thesis, an analysis of the websites of the Miroslav Krleža Lexicographic Institute would be carried out, that is, online editions of the institute's encyclopedia would be analyzed; Croatian Encyclopedia, Croatian Technical Heritage Portal (Croatian Technical Encyclopedia) and Proleksis Encyclopedia.