Using a unique sample of plant level data from the Longitudinal Research Database (LRD), we identify (for the first time in the literature), how (the precise channel and mechanism), where (parent or subsidiary), and when (the dynamic pattern) performance improvements arise following corporate spinoffs. We identify the source of value improvements in spin-offs by comparing the magnitude of post-spinoff changes in the wages, employment, materials costs, rental and administrative expenses, sales, and capital expenditures in the plants belonging to firms undergoing spin-offs relative to the magnitude of such changes in a control group of plants belonging to firms not undergoing spin-offs. We show that the total factor productivity (TFP) of plants belonging to spin-off firms (parent or spun-off subsidiary) increase, on average, following the spin-off. This increase in overall productivity begins immediately, starting with the first year following the spin-off, and continuing in the years thereafter. This performance improvement can be attributed to a decrease in workers' wages, employment at the plant, decrease in the cost of materials purchased, as well as a decrease in rental and office expenditures, but not from improved product market performance by these plants. Further, such productivity improvements arise primarily in plants that remain with the parent; plants belonging to the spun-off subsidiary do not experience such productivity increases. However, contrary to speculation in the previous literature, plants that are spun-off do not underperform parent plants prior to the spin-off. Finally, in our split-sample study of plants that were acquired subsequent to the spin-off and those that were not, we find that productivity increases for both groups of plants: while such productivity increases start immediately after the spin-off for the nonacquired plants, for the acquired plants they occur only after being taken over by a better management team.