This paper analyzes the auditor choices for a sample of 2,333 predominantly small and mid-sized Finnish firms. Finland requires virtually all commercial enterprises to have a financial statement audit, but allows the smallest firms to choose from four types of audit firms: first tier international firms, first tier national firms, second tier local auditors and non-certified auditors. We find that among the smallest firms, the choice to hire a certified auditor relates to the level of complexity in the organization as measured by size and extent of workforce. For firms that must use a certified auditor, we find that the choice between a first tier and second tier firm is related to size, the extent of debt financing, and complexity associated with being a member of an associated group. Finally, in the upper end of the market, the decision to hire a large international firm relates to size, the need for financing, be it equity or debt, and complexity due to a broad labour force. This pattern is interesting because it indicates that the need for a higher quality auditor is driven first by complexity, then as the firm grows, it is supplemented by the use of debt financing and ultimately by the need to raise equity as well as debt financing.