The crucial aim of the political economy of J.S. Mill was, according to his comments, to find ways of solving the most important social problems of his times. He believed that it was possible to improve the economic situation of lower classes and to raise the level of happiness in society. Thus, particular attention has been paid to his concepts of state intervention and projects of socio-economic reforms. Mill's projects clearly demonstrate that although Mill was definitely a political liberal himself, he was fascinated by some of the economic ideas of socialism, too. His efforts of uniting liberal and socialist economic concepts greatly contributed to the validity of the liberal approach to welfare-state concept, while Mill himself could be characterized as a forerunner of a socio-liberal style of thought, represented also by J.M. Keynes or J. Rawls.