How do banks respond to asset booms? This paper examines i) how U.S. banks responded to the World War I farmland boom; ii) the impact of regulation; and iii) how bank closures exacerbated the post-war bust. The boom encouraged new bank formation and balance sheet expansion (especially by new banks). Deposit insurance amplified the impact of rising crop prices on bank portfolios, while higher minimum capital requirements dampened the effects. Banks that responded most aggressively to the asset boom had a higher probability of closing in the bust, and counties with more bank closures experienced larger declines in land prices.