A 1:750 000 scale geological map, covering an area of over 320 000 sq. km occupied by the Republic of Karelia and adjacent areas of Northwest Russia and Eastern Finland, has been compiled for the first time. A new legend, based on the International Stratigraphic Scale, was constructed by the authors. It differs from the common legends of Russian state geological maps. The rank of Archean and Proterozoic strata, comparable in the duration of formation to Phanerozoic systems, was determined. They are described briefly with regard for modern geochronological data. New colours and numerical indexing for all the strata shown in the map were used. The multi-level geoinformation system “1:500 000 scale Southeastern Fennoscandia”, based on new geological, geophysical, geochronological and petrological data collected by the Institute of Geology and other organizations, was developed. Geodynamic models for the Archean to Paleozoic crustal evolution of SE Fennoscandia have been proposed.