Millions of children around the world are living in large residential institutions where they lack individual care and a suitable environment in which to thrive. Increased awareness of the considerable risks these children face in terms of negative social, cognitive and physical development prompted international debate regarding deinstitutionalisation and development of policy and practice that eliminate the use of such establishments. Following the demise of the Soviet Union, world attention was alerted to the situation of thousands of children living in large residential institutions across countries of the Central and Eastern Europe and Commonwealth of Independent States (CEE/CIS) region. Since this time, governments in the region have been striving to effect political and social welfare reform, including development of deinstitutionalisation policies. Analysis of regional statistics revealed a variance in deinstitutionalisation results across the region, with a noticeable difference in accomplishments of two countries in particular, Bulgaria and Ukraine. This divergence has remained largely unexplained. This study applied a comparative case study approach in order to seek an explanation of this phenomenon. A literature review allowed for an exploration of the concept of deinstitutionalisation and contextual background of post-communist countries. Fieldwork involving semi-structured interviews with child care professionals provided information on the deinstitutionalisation process in Bulgaria and Ukraine with analysis allowing for comparison of factors contributing to differences and similarities in achievements. A main conclusion of this study is that the extent and continuity of political commitment are critical to development and implementation of a country's deinstitutionalisation policy and practice. Inclusion of this factor should form an integral component of a theoretical framework for deinstitutionalisation. Findings of this study will contribute to the understanding of deinstitutionalisation policy frameworks and programming, especially in the context of the CEE/CIS region.