The article contains comparative analysis of the main tendencies in the development of modern European social democracy under the conditions of its political success, with social democracy having come to power in leading West European countries. The author concentrates his attention on the «third way» doctrine which constitutes the ideological base of European social democratic parties. He notes, in doing so, that the «third way» ideology, far from being new as such, has essentially changed in its content. Whereas formerly, the «third way» used to imply a «middle way» between Soviet «real socialism» and «orthodox American capitalism», subsequently, after the break-up of the USSR and with acceleration of the globalization processes, the search for a «third way» was transferred, to be proceeded within the market paradigm. This latter circumstance necessitates renouncement of many postulates of the post-war social democratic movement which thus assumes ever more centrist orientation. The example of T.Blair’s Labour government makes this especially noticeable. Chancellor G.Schroeder of Germany, too, advocates a more manifest market orientation of social democracy, but he has to reckon with the strong left wing in the Social Democratic arty of Germany. The firmest adherence to the principles of social justice is demonstrated by Prime Minister L.Jospin of France, with his motto: «Yes - to market economy, no - to market society».