This paper investigates capital structure and investment behavior in Thailand in the early 1990s. Various features of financial markets are considered, and the possibility of applying the 'pecking order hypothesis' to developing countries is discussed. By estimating the determinants of the capital structure and the investment functions, three major results are obtained. First, the lower debt ratio of listed firms is realized by an increase in the capital surplus gained by initial public offering. Second, firms' participation in the securities market accommodates agency costs both in the equity and bank-loan markets. Third, 'financial conglomerate' firms are inactive investors and are dependent upon informal financial transactions, whereas foreign firms borrow less and invest more. Copyright 2006 East Asian Economic Association.