A co-founder of IAB Europe in 2002 and the association's longest serving Board Chairman , Constantine currently serves as IAB Europe’s Chairman Emeritus since September 2018. He is also Project Lead at the european Online Publishers Association (OPA Europe), working with a select group of premium content providers on the association’s “Best Practices in Digital Publishing” program. In his native Greece, he sits on the Boards of leading digital companies, advising them on Strategy & Business Development as well as Corporate and Brand Communications.