Pre-print, Working paper: We explore whether financial constraints matter and which financial constraints matter the most in the choice of becoming an entrepreneur. We exploit a randomly assigned welfare program in rural Mexico to show that cash transfers significantly increase entry into entrepreneurship, thereby providing evidence of financial constraints. We then develop a simple model to highlight how liquidity and insurance constraints respond differently to the time profile of expected cash transfers. Exploiting the cross-households variation in the timing of these transfers, we find that current occupational choices are significantly more responsive to the amount of transfers expected for the future than to the amount of transfers currently received. We interpret these findings as evidence that the program has been effective in promoting micro-entrepreneurship by enhancing the willingness to bear risk.