This paper studies how liability dollarization conditions the effect of exchange rate flexibility on growth. It develops a model with credit-constrained firms facing liquidity shocks denominated in tradables while their revenues are both in tradable and nontradables. With frictions in the reallocation between tradables and nontradables, a peg is more growth-enhancing than a float in countries with dollarized debt because it stabilizes firms' cash flows and therefore allows them to face liquidity shock and complete their innovation process. However, this relative advantage diminishes when dollarization decreases. These theoretical predictions are confirmed by an empirical analysis on a panel of 76 countries spanning 1995-2004: the higher the degree of dollarization, the more negative the impact of exchange rate flexibility on growth. The empirical results are robust to various specifications and to the treatment of endogeneity.