The Centers for Disease Control and Prevention (CDC), the US Food and Drug Administration (FDA), state and local health departments, and public health and clinical stakeholders have investigated a nationwide outbreak of e-cigarette, or vaping, product use-associated lung injury (EVALI). 1 As of February 25, 2020, a total of 2,807 hospitalized cases of EVALI have been reported to the CDC from all 50 states, the District of Columbia, and two US territories (Puerto Rico and US Virgin Islands). Sixty-eight deaths have been confirmed in 29 states and the District of Columbia (as of February 18, 2020).2, 3, 4, 5, 6 Mechanisms for lung injury in this syndrome are still being investigated. Vitamin E acetate (VEA) is strongly linked to the EVALI outbreak. VEA has been found in product samples tested by FDA and state laboratories and patient BAL fluid samples tested by the CDC from geographically diverse states. VEA has not been found in the BAL fluid of people who do not have EVALI. However, evidence is not sufficient to rule out the contribution of other chemicals of concern, including chemicals in either tetrahydrocannabinol (THC) or non-THC products, in some of the reported EVALI cases. The current article summarizes evidence as of February 25, 2020, for potential toxicants and mechanisms of toxicity for EVALI.