While it is clear that the transition that has been underway in Central and Eastern Europe and Eurasia for nearly a quarter century—of which the development of civil society is an integral part—is not inevitable or uni-directional, Civil Society Organizations (CSOs) are playing a key role in responding to major regional challenges. CSO sectors in the twenty-four countries covered in the CSO Sustainability Index for Central and Eastern Europe and Eurasia continue to be highly diverse in 2015, spanning the full spectrum of sustainability. The growth of truly democratic institutions and civic space has been stunted in many countries, and has eroded in others. On the other hand, as many countries continue on a path towards membership or association with the European Union, civil society is advocating for and monitoring the implementation of democratic practices and good governance reforms. Finally, 2015 was marked with the unprecedented wave of migrants and refugees entering the continent, largely from Syria and Iraq, which affected a number of dimensions of CSO sustainability. CSOs played a key role in providing services to refugees and promoting informed public dialogue on issues related to migrants, both along the main transit routes and beyond.