This paper explores determinants of tangible long-lived asset impairments under US GAAP and IFRS. Using a sample covering 26 countries, we document that US GAAP impairments are more related to macroeconomic factors consistent with the built-in delay in reporting impairments under two-step impairment testing and measuring the impairment loss at fair value. IFRS impairments are more associated with firm-specific factors consistent with measuring the impairment at value-in-use and a one-step impairment test. Results also indicate US GAAP impairments are more associated with reporting incentives, except for having private debt. Further, when enforcement is low, impairments are less (more) associated with economic factors (reporting incentives) for IFRS reporters.