He served on the Chemistry Resource Committee of the College of American Pathologists from 2002 through 2010; he was Chair of that committee from 2007 through 2010. He was re-appointed Chair of that committee in 2012 and served in that role through 2016. He has been an active member of the CAP Accuracy-Based Committee since its inception several years ago, and he is currently its Vice Chair.
Dr. Horowitz has also worked with the Clinical Laboratory Standards Institute (CLSI): he was Chair of the working group on Document C28 (Reference Intervals) and is now Vice-Chair of the working group on Document GP27 (Using Proficiency Testing to Improve the Clinical Laboratory).
His professional interests include informatics, automation, cardiac markers, therapeutic drug monitoring, and toxicology.