This paper is about supplier development when international companies have production sites in Southeast Asia and look for opportunities to switch from international suppliers to local suppliers. We conducted a field study involving site visits to companies in Thailand and Vietnam, and interviews at corporate supply chain departments. Some key observations are: cost management was a dominant motive for taking local supplier development initiatives. Furthermore, local sourcing and local supplier development were important for international companies to improve access to local customer markets. Firms deliberately assessed whether a particular supplier would likely be able to improve sufficiently to warrant investing in supplier development, which typically involved a combination of initiatives, requiring the international firm to take considerable efforts. Local sourcing strategies and priorities for supplier development initiatives tended to focus on items with low supply risk and low volume. These findings are discussed based on transaction cost economics, and we suggest that firms use several ways to reduce the risk of transaction-specific investments in supplier development initiatives.