Mark advises clients on foreign policy dynamics, energy-sector politics, and post-conflict governance. His expertise spans public diplomacy, cross-cultural engagement, and stabilization efforts in fragile states, with a particular focus on Equatorial Guinea and Central Africa.

Mark brings nearly four decades of diplomatic experience, including service as US Ambassador to Equatorial Guinea (2012–2015), where he built high-level relationships. For his service, he was awarded Equatorial Guinea’s highest civilian honor, the Grand Cross of the Order of Independence.

Before joining Horizon Engage in 2016, Mark held senior diplomatic roles, including Deputy Chief of Mission in Sudan and Kazakhstan and Chief of Staff in the Office of the Under Secretary for Civilian Security, Democracy, and Human Rights. He also served as Deputy Coordinator for Reconstruction and Stabilization, leading conflict mitigation and recovery efforts.

Mark is the author of Spanish Connections: My Diplomatic Journey to Equatorial Guinea (Xlibris, 2023), a memoir that explores his ambassadorship and US-Africa relations. He holds a PhD in American Studies from Brown University and has served as a Fulbright Lecturer in Spain and Senior Public Diplomacy Fellow at George Washington University.