This article asks how policy learning is achieved and whether and how it impacts on policy change. By drawing on the empirical case of Belgian mental health reforms, it shows that policy learning occurs through the very practice of policy-making. In-depth analyses of the process of preparing and devising, a current reform of mental health care delivery, called Reform 107, evidence that the transformation of policy learning – through verbal expression, inscription in documents or enactment in social situations such as meetings – is crucial to its impact on policy change. A phenomenological approach to knowledge in policy helps to perceive and describe the transformation of policy learning through practical actions and interactions involved in devising policy change. Analytically, looking at this transformation entails shifting the focus from big and visible changes in policy objectives and instruments to micro policy practices such as meeting and writing documents. Placing the focus on micro policy practices should not lead, however, to a disregard for the social context in which they develop. The interactionist concept of linked ecologies provides the means to consider social regulations influencing policy learning without underestimating their very ephemeral and contingent nature.