We analyze comprehensive manufacturing firm data to measure the contribution of inter-firm employment reallocation to aggregate productivity growth during the socialist and reform periods in six transition economies. Modifying a standard decomposition technique to better reflect the role of firm entry, we find that reallocation rates and productivity contributions are very low under socialism, but they rise dramatically after reforms, and productivity contributions greatly exceed those observed in market economies. Early in transition, more reform is associated with larger contributions from reallocation, but later, and on average over the whole transition, this relationship is reversed. Though reallocation rates are larger in faster reforming economies, higher productivity dispersion in slower reformers creates higher productivity gains for a given volume of reallocation. The results imply that reallocation should be viewed as necessary regular maintenance for a well-functioning economy, and patticularly large productivity contributions tend to reflect previous neglect more than current virtue.