This study examines the impact of managers' incentives and corporate diversification on the returns to shareholders of acquiring firms in acquisition activities. Managers' incentives are measured by creating an incentive ratio (IR). The IR is constructed by dividing the market value of the equity holdings of the three managers with the largest equity shareholding within the firm by their annual compensation. We hypothesize that managers with a high IR are more likely to undertake acquisitions that benefit the shareholders of the acquiring firm than are managers with a low IR. We further hypothesize that the acquisition of a firm that is a focused acquisition (i.e., same industry) will produce greater returns to the acquiring firm's shareholders than will diversified acquisitions. Results indicate significant positive returns to acquiring firms whose managers have high IRs. While diversified acquisitions produce insignificant negative stock returns, focused acquisitions, on average, generate significant positive stock returns for acquiring firms. Results also suggest that managers with a low IR consistently undertake more diversified acquisitions than focused acquisitions, that the group with the combination of high IRs and focused acquisitions produces the highest returns among four groups, and that the group with the opposite combination produces the lowest returns.