We study the asset pricing implications of a multi-agent endowment economy where agents can default on debt. We build on the environment studied by Kocherlakota (1995) and Kehoe and Levine (1993). We present an equilibrium concept for an economy with complete markets and with endogenous solvency constraints. These solvency constraints prevent default, but at the cost of reduced risk sharing. We show that versions of the classical welfare theorems hold for this equilibrium definition. We characterize the pricing kernel, and compare it to the one for economies without participation constraints: interest rates are lower and risk premia depend on the covariance of the idiosyncratic and aggregate shocks.