This presentation will briefly review previously published research on molecular phenotypes of ARDS, including the hyper-inflammatory and hypo-inflammatory phenotypes identified using latent class analysis, as background.  The majority of the presentation will focus on recently published or unpublished new data on ARDS molecular phenotypes, including data related to generalizability, feasibility of identification, potential mechanisms, and relevance to COVID-19 ARDS.  The presentation will conclude with some thoughts on future directions in research on this topic and how molecular phenotypes might be targeted in clinical trials.