This paper studies the evolution of the land tenure institutions of Bulgaria, an Eastern European country in transition from a socialist centrally planned to a capitalist market economy. The focus is on the period 1839–1878 during which the country was still under Ottoman rule and on the period after liberation, 1878–1944. The major factors which determined the shape of these institutions and the mechanisms of transition between land tenure regimes are identified and analyzed by critically evaluating two theories of institutional change — the efficiency theory developed by Demsetz (1967) and the social conflict theory developed by Acemoglu, Johnson, and Robinson (2005). Consistent with the latter theory, the paper argues that political institutions and the distribution of resources determined the prevailing political balance which in turn determined the structure of land tenure institutions during those two periods. The process of institutional change during 1839–1878 was endogenous to the Ottoman Empire but exogenous to Bulgaria as the institutions of the latter were embedded into those of the former. The shift to the post-liberation land tenure regime (1878–1944) was an endogenous process but the initial source of prevailing political power was an external factor — the Russian occupation forces. The paper suggests that the social conflict theory be expanded to include the embeddedness factor and the role of external factors in the process of institutional change.