What conditions drive or impede the transfer and reception of laws and how? Inother words, what is the social explanation of legal transplantation - one of the most common forms of legal change? The answers to these questions are important not only for social and legal scholars, but also for designers of legal reforms. This book presents an interdisciplinary attempt to explain the legal transplantation process by identifying conditions that shaped transplantation of EU regulatory rules to Central Eastern Europe. Based on a critical review of literature, the author developed an analytical framework for describing the pattern of legal transplantation. The comparison of general approximation in Lithuania and Poland revealed the determining importance ofinstitutional and ideational conditions, whereas structural and psychological conditions, differently from what is often claimed in the literature, appeared to be less important. Indeed, during the early period of integration, both countries opted for American legal transplants despite growing proximity with the EU. During pre-accession institutional and ideational conditions were responsible for delay in approximation in Lithuania and progress in Poland. Analysis of transplantation of EU competition policy and state aid control rules confi rmed the importance of institutional and ideational conditions,although diff erent from sets of conditions in general approximation process. It is concluded that legal transplantation patterns are better explained by arguments relying on institutional and ideational logic, rather than on structural or psychological, and that sets of shaping conditions differ per policy area and phase of the transfer process.