Using administrative data on Taiwanese lottery winners, this paper examines the effects of cash windfalls on entrepreneurship. We compare the start-up decisions of households winning more than 1.5 million NTD (50,000 USD) in the lottery in a particular year with those of households winning less than 15,000 NTD (500 USD). Our results suggest that a substantial windfall increases the likelihood of starting a business by 1.5 percentage points (125% from the baseline mean). Startup wealth elasticity is 0.25 to 0.36. Moreover, households who tend to be liquidity-constrained drive the windfall-induced entrepreneurial response. Finally, we examine how households with a business react to a cash windfall and find that serial entrepreneurs are more likely to start a new business but do not change their decision to continue the current business.