Does limited access to formal savings services impede business growth in poor countries? To shed light on this question, we randomized access to non-interest-bearing bank accounts among two types of self-employed individuals in rural Kenya: market vendors (who are mostly women) and men working as bicycle taxi drivers. Despite large withdrawal fees, a substantial share of market women used the accounts, were able to save more, and increased their productive investment and private expenditures. We see no impact for bicycle- taxi drivers. These results imply significant barriers to savings and investment for market women in our study context.