Basic research has identified numerous inflammatory pathways that are associated with the development of ARDS. Agents that block these mediators prolong survival in animals with lung injury, and a few of them have been tested in patients. Because of the large number of putative mediators and the variety of ways that their action can be blocked, the possibility for new drug development is almost infinite. This is an exciting prospect, since it envisions the first effective pharmacologic treatment for ARDS. However, preliminary clinical studies have shown conflicting results, and there is an urgent need for a mechanism to efficiently and effectively test new drugs in ARDS.