We estimate the real effects of UK guarantees introduced during 2009 by exploiting firm-size eligibility restrictions and rich administrative data. Relative to matched non-eligible firms, eligible businesses had higher 5-year debt and performance, yet similar repayment and interest rates. Employment, wages, and productivity also increased, yet there was no impact on pledgeable asset investment, even for capital-dependent firms. The evidence suggests that the guarantees relaxed credit constraints by enabling firms to access loans they could not obtain otherwise at any rate, especially for financing workers. We find no evidence supporting other mechanisms like debt-cost decreases, changes in incentives, or externalities.