In this paper we follow an income-based, time-dependence approach to measure the impact of entrepreneurship on social mobility in Uruguay. The working definition of entrepreneur is business owners with employees. Using household surveys from 1982 to 2010 we show that their income level, income volatility, and evolution over the business cycle are consistent with them being opportunity entrepreneurs. Self-employed workers are more similar to necessity entrepreneurs. We find significant evidence that entrepreneurship is associated with greater social mobility while self-employment is not.