Before joining the Research Institute for Languages and Cultures of Asia at Mahidol University, Bangkok, he was a senior researcher at Max Planck Institute for the Study of Religious and Ethnic Diversity in Göttingen, Germany, where he remains as research partner. He is currently member of a research team led by Decha Tangseefa (Thammasat University) on the Karen refugee crisis funded by the Thailand Research Fund. Alexander spent many years in Thailand, speaks Thai, and did his ethnographic fieldwork primarily in the mid-South and now Northwestern Thailand and Southeastern Burma.

Alexander Horstmann is author of Class, Culture and Space: The Construction and Shaping of Communal Spaces in South Thailand (transcript, 2002) co-editor (with Günther Schlee) of Integration through Diversity, co-editor (with Reed L. Wadley) of Centering the Margin: Agency and Narrative in Southeast Asian Borderlands. Oxford, 2006, co-editor (with Katherina Seraidari) of Intimacy and Violence: Fragile Transitions in Southeast Asia and in Southeast Europe, Oxford, fc and co-editor in chief of the new journal Conflict and Society: Advances in Research, published by Berghahn, from 2012.

He published in numerous peer-reviewed international journals, such as SOJOURN, Journal of Southeast Asian Studies, Journal of Borderland Studies, Encounters and Journal of Refugee Studies. His most recent publications include [2011] "Ethical Dilemmas and Interactions of Faith-Based Humanitarian Organizations in the Myanmar-Thailand Borderland: The Example of the Karen Refugee Crisis", in: Journal of Refugee Studies, Special Issue Faith-Based Humanitarianism in Contexts of Forced Displacement, published in September as Vol. 24, No 3 and [2011] "Living together: The Transformation of Multi-Religious Coexistence in Southern Thailand", in: Journal of Southeast Asian Studies, published out in October 2011.