Over the course of 100 years the main goals set for the Polish Geological Institute were subject to important changes depending on knowledge of the geological structure of the country, current demand for mineral raw materials and the economic system of the state. The first period comprised the years 1919-1952. It was characterized by the increased emphasis on geological cartography as well as basic research and regional studies. Its main effects included compilation of a geological map of Poland at the scale of1:300,000 and discoveries of new mineral deposits (hematite-pyrite deposit at Rudki, phosphorites at Rachów, bituminous coal in the Lviv-Volhyn coal basin, present-day Ukraine, and the Izbica-Klodawa salt dome. The second period comprising the years 1953-1989 was a time of an immense geological work. During that period priority was given to prospecting and exploration of mineral resources at any price. This resulted in an impressive discovery of mineral deposits, such as: native sulfur, copper and silver, sedimentary and igneous iron ores, bituminous coal, lignite, oil and gas fields, as well as potassium salt, barite, fluorite, magnesite and Cu-W-Mo ores. An effect of political changes in 1989 was a change of concept regarding prospecting and exploration of mineral resources. The state resigned from development and documentation of resources, leaving this task to private companies and investors. This launched a new third period that has continued to this day. During this time, data collection and processing, and their availability to a broad range of recipients have had a fundamental role. This is consistent with the concept of building an information society. Major new lines of activity of the Polish Geological Institute include protection of the environment, especially a soil-water environment that is the traditional domain of geologists, monitoring of groundwater, soil and bottom sediments as well as solid waste management. Geological education and protection of the geological and mining heritage have also assumed a vital importance.