This paper deals with credit market imperfections and idiosyncratic risks in a two-sector heterogeneous agent dynamic general equilibrium model of occupational choice. We focus especially on the effects of tightening financial constraints on macroeconomic performance, entrepreneurial risk-taking, and social mobility. Contrary to many models in the literature, our comparative static results cover a broad range for financial constraints, from an unrestrained to a perfectly constrained economy. We find substantial gains in output, welfare, and wealth equality associated with credit market improvements. The marginal gains from relaxing constraints are largest for empirically relevant debt-equity ratios. Interestingly, the entrepreneurship rate and social mobility respond non-monotonically to a change in the tightness of financial constraints. The results crucially depend on feedback effects in general equilibrium, where optimal firm sizes and the demand for credit are endogenously determined.