This paper analyses the impact of credit information sharing on financial stability, drawing special attention to its interactions with credit booms. A probit estimation of financial vulnerability episodes-identified by jumps in the ratio of non-performing loans to total loans-is run for a sample of 159 countries divided into two sub-samples according to their level of development: 80 advanced or emerging economies and 79 less developed countries. The results show that: i) credit information sharing reduces financial fragility for both groups of countries; ii) for less developed countries, the main effect is the direct effect (reduction of NPL ratio once credit boom is controlled), suggesting a portfolio quality effect; iii) credit information sharing also mitigates the detrimental impact of a credit boom on financial fragility but this result holds only for advanced and emerging countries and for household credit booms; and iv) the depth of information sharing has a negative impact on the likelihood of credit booms (but not the coverage of IS).