What determines the pace of policy innovation and change? Why, in other words, do policy makers in some countries innovate faster than in others? This thesis challenges conventional explanations, according to which policy change occurs in response to class conflict, partisan preferences, power of professional groups, or institutional and policy legacies. The thesis instead argues that different paths of policy change can be best explained by the different learning processes by which policy makers develop ideas for new policies in reaction to old policies. The thesis draws upon both ideational and institutional streams of literature on policy change, and develops its argument that policy change, understood as a learning process, is a result of interactions between three different, yet interdependent factors – ideas, interests and institutions. The thesis explores this argument by investigating in detail two radical cases of policy innovation – the introduction of market-oriented elements in Czech and Polish healthcare policy during the first two post-communist decades. The selection of the two cases is based on the methodological rationale of the 'most similar system design', given that the healthcare systems of the two countries were both state-dominated under communism, while in the post-communist period the governments of the two countries introduced market-oriented reforms that followed rather divergent policy paths. While Czech reforms were relatively consistent and comprehensive, those in Poland were fragmented, delayed and beset with reversals. The thesis looks at these two cases of healthcare reforms from a long-term historical perspective, covering the inter-war, the communist and, most thoroughly, the post-communist period. It draws upon the official documents, secondary literature and more than 40 interviews with policy making elites, and compares the two policy paths using small-N research design, causal analysis and process tracing techniques. The main finding of the thesis is that the market-oriented ideas that occurred in healthcare policy circles during the 1970s and 1980s were crucial drivers of the post-communist reforms in the two countries. However, the capacity of these ideas to serve as a basis of policy change was dependent on two factors – on the existence of political actors who were willing to promote these ideas, and on the interaction of institutional veto points with the electoral and partisan dynamic. The findings of this thesis contribute to the better integration of the literatures on the role of ideational and institutional factors in policy change, and to the research on the causes and consequences of marketization in healthcare and, more broadly, in social policy.