In this thesis I study patterns of inter-organisational collaboration among nonprofits in Czech Republic and Poland. Point of departure constitutes puzzling divergence in patterns of collaboration between these two countries. Cluster analysis conducted on unique set of quantitative data revealed that in Czech Republic significantly more nonprofits manifest "strongly collaborative" pattern than in Poland. Those nonprofits have particularly well developed collaborative ties to the government. Interestingly, close collaboration with government do not come at the expense of local ties and accountability to the citizens. Existing regional nonprofit literature has not captured national differences in this respect. Explaining this puzzling divergence constitutes the main goal of this thesis. Building on rational choice and sociological institutionalism I assume that two actors played a central role in shaping patterns of inter-organisational collaboration of nonprofits in Central Europe, i.e. domestic government, through its "nonprofit policy", and the European Union, through its main developmental instrument, European Union Structural Funds ("EU SF"). Based on the extensive literature review, analysis of secondary data and more than 50 semi-structured interviews conducted in Poland and Czech Republic I argue that divergence in patterns of collaboration is a consequence of differences in resources and opportunities provided to the nonprofit organizations by domestic governments and EU. Strong ties to the government of the significant part of Czech nonprofit sector are a consequence of relatively generous and centralised public funding available for those organizations, institutionalized opportunities for participation in policy making and activism of the nonprofit community in the pre-accession period. Weak collaborative ties of Polish nonprofits are a result of scarcity and decentralisation of public funds, very limited opportunities for shaping public policy and general distrust towards collaboration with government among the leaders of Polish nonprofit community as well as their limited activism during pre-accession period.