Co-Organizers: Neil L Kelleher, Northwestern University and Ljiljana Paša-Tolić, PNNL Top Down mass spectrometry is a classical approach to molecular analysis, but is reborn in the contemporary context of protein analysis. Top Down now stands at a turning point – somewhat beyond an emerging technology, but yet difficult to implement vs. more widely used Bottom Up approaches to protein and proteome interrogation. For proteomics, Top Down strives to preserve the forms of proteins present in vivo by measuring them intact, rather than measuring peptides produced from them by proteolysis, with the largest impact thus far felt in chromatin biology via Top Down and Middle Down analysis of histones. For single biopharmaceutical targets that are highly modified, Top Down continues its acceleration toward an accepted, even wide-spread practice. This meeting will bring together novice and seasoned practitioners in the field of Top Down mass spectrometry with the goal to outline recent approaches and applications and provide an outlook for its future.