The paper about the development of the market of public pension societies in Poland consists of an introduction followed by four parts: 1. The reform of the old-age pension system in Poland, 2. Public pension societies as institutional exemplification of the reform of the old-age pension system in Poland, 3. Legal, institutional, ownership, and economical changes, and, 4. The influence of the accession of Poland to the European Union on the changes in the public pension societies market. The research objective of the article was to present the shaping of the market of public pension societies in Poland in relation to the sources of its growth, typical institutional organization, legal, institutional, ownership and economic changes, as well as to highlight the changes within the public pension societies in Poland in the context of the accession of the country to the E.U. In the résumé the author presents arguments that the old-age security solutions accepted in Poland fully reflect the indications of the World Bank regarding the construction of the old-age pension systems. The changes of legal regulations concerning the capital-based pension system, introduced in 1997, by a series of revisions to the Act, did not apply to operation of public pension societies. The institutional changes consisted of the reduction of the number of the operating entities from 21 in 1999 to 15 at the end of 2004. The ownership changes took place in the way that was characteristic to market economy and no particularly stong presence of investors from any single country was observed. The economic changes related to the stabilization of the share capital, the increase of the volume of own funds, and achieving net profit in 2002. The accession of Poland to the E.U. in 2004 did not bring about changes in the operation of the public pension societies due to the application by the European Union of the so called open co-ordination method.