Mertens is Professor Emeritus at Gallaudet University with a specialization in research and evaluation methodologies designed to support social transformation. She has authored, co-authored, or edited many books related to evaluation methods and human rights, most recently Program Evaluation Theory and Practice 2nd ed; Mixed Methods Design in Evaluation; Research and Evaluation in Education and Psychology: Integrating Diversity with Quantitative, Qualitative, and Mixed Methods 5th ed.; Indigenous Pathways into Social Research, and Transformative Research and Evaluation.She focuses on the intersection of evaluation with social justice and human rights within the philosophical assumptions of the transformative paradigm.
Mertens served as the eEditor for the Journal of Mixed Methods Research 2010–-2014. She was President of the American Evaluation Association in 1998 and served on the Board from 1997 to -2002; she was a founding bBoard member of the International Organization for Cooperation in Evaluation and the Mixed Methods International Research Association.