This paper tests whether demand shocks affect firm dynamics. The authors examine whether firms that win government procurment contracts grow more compared to firms that compete for these contracts but do not win. They assemble a comprehensive data set combining matched employer-employee data for the universe of formal firms in Brazil with the universe of federal government procurement contracts over the period of 2004 to 2010. Exploiting a quasi-experimental design, they find that winning at least one contract in a given quarter increases firm growth by 2.2 percentage points over that quarter, with 93% of the new hires coming from either unemployment or the informal sector. These effects also persist well beyond the length of the contracts. Part of this persistence comes from firms participating and winning more future auctions, as well as penetrating other markets.