We analyze changes in investment policy following 106 spinoffs between 1981 and 1996. Pre-spinoff, the sample firms are valued at a discount and invest less in their high q segments than do their single-segment peers. Post-spinoff, there is a significant increase in measures of investment efficiency and the diversification discount is eliminated. Furthermore, changes in excess value around the spinoff are positively related to changes in measures of investment efficiency. These findings support the view that (i) diversified firms allocate investment funds inefficiently, and (ii) by breaking up the conglomerate, spinoffs create value by improving investment efficiency.