He was President of the Ukrainian American Association of University Professors from 1981 to 1984 and again from 2004 to 2012 and Vice President of the Ukrainian Academy of Arts and Sciences, chairing its history section.[3] He headed the World Scholarly Council at the Ukrainian World Congress and was a full member of the Shevchenko Scientific Society.[1] In 1965 he founded the Ukrainian Historical Association (UHA), a non-profit organization which he also directed.[3] In 1989, he became a member of the executive committee of the Ukrainian National Council, leading its academic field.[1]
He wrote and edited more than 85 books on Ukrainian history and published more than 2000 articles.[3]