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This blog interview series was developed and is curated by Cristina Repede. It is an initiative of the Emerging Evaluators Thematic Working Group (TWG) of the European Evaluation Society (EES), published in partnership with EvalYouth Europe, and reflects EES’s ongoing commitment to spotlight diverse voices and experiences within the evaluation community.

Today we share part 1 of the interview with Thomas Delahais. This first part focuses on understanding his background and perspective on evaluation, while part 2 will offer recommendations for evaluators looking to grow in the field.

In his 20 years of experience, Thomas Delahais has been committed to developing pragmatic ways to evaluate complex interventions and learning from them. He has helped to operationalise theory-based approaches like contribution analysis, applying it to a range of interventions, including sustainable transition initiatives, transport infrastructure, research, and governance. In 2013, he cofounded Quadrant Conseil, a cooperative company specialised in policy evaluation and design.

 1. What is your area of specialization in evaluation, and how did you embark on your career as an evaluator?

I’m what you’d call an accidental evaluator. I never intended to become one; as a child, I certainly didn’t dream of evaluation as a career. I initially trained in political science and later in city planning. But when I graduated, I couldn’t find a job in my field. Around that time, an opportunity came up to work with an evaluation consultancy. That was 21 years ago, and I’ve been in the field ever since.

In terms of specialization, I wouldn’t say I’m a thematic evaluator, I don’t focus on a specific sector. Rather, my expertise lies in methodological approaches. I’ve worked extensively on impact evaluation methodologies, especially the plurality of approaches available, and I’ve been involved with contribution analysis for about 15 years now. I’m also deeply interested in how evaluation is used in policymaking, which has become an important focus for me.

While I’ve worked on a wide variety of topics over the years, I have a long-standing interest in sustainable transitions, particularly bottom-up initiatives, efforts that experiment with new ways to drive and sustain meaningful transitions at the local or grassroots level.

2. Could you tell me about your current workplace and your role there?

Yes, I co-founded Quadrant Conseil in 2013 along with three other colleagues. We set it up as a worker-owned cooperative, which is still quite rare in Europe, though somewhat more common in France. The idea behind this model is that everyone who works at Quadrant Conseil is, or can become, a co-owner. We make decisions collectively, and for us, this structure is very important: we believe evaluators should have true ownership over their work and their workplace. Right now, we’re 18 people, and 12 of us are cooperative members.

3. On your website, I noticed that you and about 10 others are listed as “associés.” It wasn’t immediately clear that you’re one of the founders. Could you explain how the structure works, particularly the roles of consultants versus associates?

Yes, that’s a good observation. Most of the consultants in the team are still early in their careers, and it usually takes two to three years before they choose to become partners. Importantly, it’s a decision that has to come from them, we don’t impose it.

We also don’t feel the need to highlight who the founders are. What matters to us is that younger evaluators feel empowered and have a sense of shared ownership. It’s their company just as much as it is mine, and we expect them to act with that mindset. That’s really the spirit of the cooperative, not just legally, but culturally.

4. Looking back, what were the key turning points that shaped your own career? Were they strategic moves, unexpected opportunities?

I think, for me, it’s mostly been a matter of encounters, meeting the right people at the right moments. One of the biggest turning points was the creation of Quadrant Conseil. That marked the shift from being an employee to trying to build something of my own. It was a major change in perspective and responsibility.

Before that, I spent ten years at Euréval, a company founded by two very experienced evaluators, Éric Monnier and Jacques Toulemonde[1]. I learned a great deal from them; it was a formative time. In fact, we conducted some of the first contribution analyses with Jacques, which had a big impact on my methodological development. That kind of learning, directly from experienced people, has been incredibly important in my journey.

More recently, around five or six years ago, I had the chance to meet Elliott Stern, a highly respected figure in the field and a very experienced editor. That encounter brought me back into the European sphere, which I had worked on a lot in the late 2000s and early 2010s but had stepped away from for about seven or eight years.

Now, through that renewed involvement, I’ve moved into something slightly different: I’m doing less direct evaluation work and more support to evaluation departments. These teams often face very complex and difficult questions, and my role is to help them navigate that, especially when they feel uncertain about how to move forward. It’s a new phase for me, but still very connected to evaluation practice.

[1] Co-founders of the European Evaluation Society, founded in 1992, and the French Evaluation Society created in 1999.

5. You’ve worked on complex, often first-time evaluations with high policy stakes. What draws you to these kinds of projects, and how do you approach them differently from more standard assignments?

It started quite early for me. At Euréval, where I began my career as a junior evaluator, I was immediately assigned to very complex evaluations. I wasn’t given simple project evaluations to start with. Instead, I was thrown into large, multi-instrument policy evaluations with long time horizons and many layers. When you’re young, you just take the assignment and dive in, but over time I realized how much I was drawn to these kinds of complex ecosystems.

What I find compelling in these situations is the challenge of making sense of the policy, not just for myself as an evaluator, but also for the people who implement it. Very often, they don’t have the full picture. They’re working on narrow components or isolated instruments, and lack a broader understanding of how their work fits into the whole. Helping them see that bigger picture can be incredibly meaningful and, frankly, rewarding.

And you can’t approach this kind of work with a standard toolkit. You can’t just say, “We’ll do some interviews and a few case studies” and be done. You need to take time. You need to observe, listen, and reflect almost like an investigator. Sometimes I joke that it feels a bit like being Columbo, wandering around, asking questions, paying attention to details that don’t seem to matter until they do. I probably even have the same coat!

To work effectively in this kind of setting, you need to be iterative, humble, and curious. You often discover insights that are interesting from an analytical standpoint, but not necessarily what stakeholders are looking for. So you have to balance what you find fascinating with what is actually useful to others. It’s not about making sense just for yourself. The real success is when your reframing resonates with others, when it enables collective understanding or sparks a new dynamic for change.

This ties closely to my work with sustainable transition initiatives which try to shift systems of energy, food, or consumption. Often, they’re seen as too idealistic or unconventional. Part of the evaluator’s job is to challenge those views constructively. If you do it well, you can help demonstrate that these “unusual” approaches might, in fact, produce better outcomes than traditional models.

In France, Bruno Latour once described innovations as hopeful monsters. That metaphor really speaks to me. These innovations are strange, messy, not fully formed, but sometimes they carry powerful insights or potential. I like working with hopeful monsters.

That said, navigating this complexity comes with risks. When your evaluation offers a new perspective that doesn’t align with the existing political agenda, it can be unwelcome, even threatening. I’ve experienced this firsthand. In one case, after months of collaborative work and broad agreement among technical teams, the top of the administration simply rejected the conclusions. Not because the evaluation was poor, but because it didn’t serve their strategic interest. They tried to discredit the methodology and push us to change the findings. We didn’t.

Experiences like that teach you the importance of not working alone. In complex evaluations, you need allies, people who support your work and help carry the load when things get politically sensitive. And you need to be prepared for failure, even when the technical quality of your work is strong. When things don’t go well, it’s easy to internalize that and think you’ve failed personally. Often, it’s just the nature of working in politically charged environments.

We don’t talk enough about failure in our field. Everyone shares their best cases, but we learn most from the ones that go wrong. That’s why having a space to reflect, to talk openly about difficulties, is essential, especially for younger evaluators.

Which brings me to something I always tell my colleagues: in this profession, you’re constantly starting fresh. Every evaluation is new — a new topic, a new team, a new client. That means you’re never fully in control, never fully prepared. The goal isn’t perfection. The goal is to ask: What frustrated me in this evaluation? What didn’t work the way I hoped? And how can I do better next time? That’s how you grow.

Because truthfully, we’re always missing something: the lack of time, of data, of budget… It’s a job that demands pragmatism, but too much pragmatism can lead to frustration. So we each need to find ways to build our own agenda over time, to keep our curiosity and ideals alive even within constraints.

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[1] Co-founders of the European Evaluation Society, founded in 1992, and the French Evaluation Society created in 1999.