‘Evidence-based’ development policy has caused impact evaluations to prioritise accountability over addressing processual learning questions. Moreover, evaluation scholarship is dominated by surveys, whereas qualitative research remains scant. This article traces one particular evaluation, within the independent Evaluation Department of the Dutch Ministry of Foreign Affairs. It asks, ‘How do evaluators and policymakers interact and what adjustments follow from the illustrative evaluation?’ It used participant observations, documents and interviews with policymakers and evaluators. An in-depth thematic analysis resulted in a typology of evaluator roles: (1) knowledge broker, (2) facilitator, (3) archive, (4) truth-revealing and (5) critical voice. Finally, policymakers and managers adjusted in three ways: symbolic, instrumental and empowerment. These results imply that if evaluators deliberate a suitable role, they (1) increase their partial understandings of the programme under scrutiny and the involved stakeholders, and (2) enhance the potential of synergies in collective learning to emerge in an evaluation team and the broader institution.

“以证据为基础”的发展政策导致影响评估将问责制置于解决过程学习问题之上。此外，评估学术以调查为主，而定性研究仍然很少。本文追溯了荷兰外交部独立评估部门内的一项特定评估。它问道，“评估者和政策制定者如何互动，说明性评估会做出哪些调整？” 它使用了参与者的观察、文件和对决策者和评估者的采访。深入的主题分析产生了评估者角色的类型学：（1）知识经纪人，（2）促进者，（3）档案，（4）真相揭示和（5）批评声音。最后，政策制定者和管理者以三种方式进行调整：象征性、工具性和授权。