This paper analyzes how default externalities lead to an excessive incidence of systemic private debt crises. An individual defaulting borrower does not internalize that her default leads to a depreciation in the exchange rate because international lenders will sell any seizable assets and flee the country. The exchange rate depreciation in turn reduces the value of non-tradable collateral and induces other borrowers to default, leading to a chain reaction of defaults. The inefficiency in default spillovers can be corrected by strengthening the enforcement of creditor rights, so that individual agents default less often, reducing the frequency of systemic default.