Drew Koleros

Drew Koleros is a systems change evaluator with over 20 years of experience designing and delivering mixed-methods evaluations and program monitoring, evaluation, and learning systems for small- and large-scale initiatives. He brings particular experience and expertise in using theory-based approaches that integrate complex concepts and systems thinking into program and evaluation design processes. His recent work centers on supporting public sector and philanthropic initiatives designed to drive systems change and tackle complex societal challenges, ranging from safe and affordable housing to climate adaptation and mitigation to advancing equitable health and education outcomes.

Koleros specializes in the design and application of theory-based and systems-oriented evaluation methods that make complex change processes visible and actionable to a broad range of system actors. He has advanced the use of system mapping approaches—combining actor-based theories of change, causal loop diagrams, and political economy analysis—to help funders and partners understand the dynamics of the systems they seek to influence, identify leverage points for entry, and how to robustly evaluate the impacts of their system change efforts. He has also applied and adapted a wide range of rigorous non-experimental causal pathways methodologies to strengthen causal claims about the contribution of initiatives to observed changes vis-à-vis other contextual factors. To ensure that evidence informs strategy, he integrates participatory sensemaking processes and innovative reporting formats, such as interactive ecosystem maps and tailored analytical briefs, that make complexity accessible to diverse stakeholders.

These methods have been applied across a wide range of philanthropic initiatives. For the Gates Foundation’s Climate Adaptation Advocacy Portfolio, Koleros supported a systems change evaluation that used system mapping and causal pathways analysis to examine how global advocacy influences adaptation financing and policy commitments. For the IKEA Foundation’s support to the Clean Cooling Collaborative, he designed an actor-based theory of change and ecosystem mapping approach to understand entry points for transforming the cooling sector. With the Robert Wood Johnson Foundation’s Transforming Public Health Data Systems Initiative, he combined causal loop diagrams with actor-based approaches to analyze system dynamics and evaluate the collective impact of a portfolio of grantees to changes in the public health data system.

Koleros has also supported multiple foundations in designing strategy-level theories of change to inform their Monitoring, Evaluation, Learning (MEL) initiatives. For example, he served as the lead facilitator for developing the theory of change as part of the Family Planning Strategy Refresh for the Bill & Melinda Gates Foundation.

He is also a skilled facilitator and trainer with extensive international experience working across diverse stakeholder groups. This includes serving as an instructor for the United Nations System Staff College, where he designed and delivers micro-credential courses on Theories of Change and Theory-based Evaluation for UN evaluation staff; a trainer for the UK Evaluation Society, where he co-designed and co-delivered short courses on Theories of Change and Contribution Analysis; and a lecturer at Boston College's Lynch School of Education & Human Development, where he designed and delivers a graduate-level course on theory of change.

Koleros holds a master’s degree in public health from the Tulane School of Public Health and Tropical Medicine and served as a Peace Corps Volunteer in Cameroon (2003–2005). Before joining Mathematica, he was the Director of Research, Monitoring and Evaluation for Palladium’s Europe, Middle East and Africa Regional Office, where he provided overall technical leadership and direction in the design and delivery of evaluations and programs. His work on designing theory-based evaluation approaches has been published in the American Journal of Evaluation, the Canadian Journal of Programme Evaluation, and in multiple practitioner settings.

He is a member of the American Evaluation Association, the European Evaluation Society, and the Canadian Evaluation Society. He serves as a Network Member of the Thinking and Working Community of Practice and the Causal Pathways Initiative.

Selected Papers and Publications

Koleros, A. (2024). Strategy-level theories of change require a focus on system change: an actor-based approach can help. In A. Koleros, M.H. Adrien & T. Tyrrell (Eds.), Theories of Change in Reality: Strengths, Limitations, And Future Directions. Routledge.

Koleros, A., Adrien, M.H., & Tyrrell, T. (Eds.) (2024). Theories of Change in Reality: Strengths, Limitations, And Future Directions. Routledge.

Ton, G., Taylor, B. & Koleros, A. (2022). Assessing the Contribution to Market System Change of the Private Enterprise Program Ethiopia. IDS Bulletin, Vol 53 No. 1 February 2022.

Koleros, A. (2021). Accountable for Adaptation: How Independent Evaluation Can Support Adaptive Programming within Bureaucracies. In B. Perrin & T. Tyrrell (Eds.), Changing Bureaucracies: Adapting to Uncertainty, and How Evaluation Can Help (pp. 58-76). Routledge.

Koleros, A. (2021). Using a Wide Lens to Take a Long View: How Integrating Systems Thinking into Evaluations Can Assist in Taking a Long-term Perspective. In K. Forss, I. Lindkvist, & M. McGillivray (Eds.), Long Term Perspectives in Evaluation: Increasing Relevance and Utility (pp. 69-87). Routledge.

Koleros, A., & Mayne, J. (2019). Using Actor-Based Theories of Change to Conduct Robust Evaluation in Complex Settings. Canadian Journal of Programme Evaluation, 33(3), 292-315.

Koleros, A., Mulkerne, S., Oldenbeuving, M., & Stein, D. (2020). The Actor-Based Change (ABC) Framework: A Pragmatic Approach to Program Theory in Complex Systems. American Journal of Evaluation, 41(1), 34-53.