Ministerial advisers are the specially appointed individuals working for ministers. As such they are an integral part of political-partisan and governmental elites, although they mostly stay hidden from view. As a distinct category of actors, they do not receive a lot of scholarly attention and there are still many blind spots as to their contributions to policymaking processes. However, in Belgium, it was demonstrated that ministerial advisers were key players in the formulation of policies at the level of governments. In some ways, approaching them is tantamount to focusing on the main venues of policy formulation, where decisive policy work is carried out and where important arbitration between a range of policy options is realized. As much as they are producers of advice destined to their ministers, ministerial advisers are also receivers of policy relevant knowledge. They are notably active in the coordination of internal and external sources of advice. Yet, exposure to policy-relevant information and advisory linkages with a series of actors more or less distant from government, might lead them to adopt a different view about the policies they actively prepare. They might change their appreciations of the various elements constitutive of policies. Such cognitive dynamics, consisting in updating beliefs about policies, are typically referred to as policy learning. This research thus asks the following question: What are the learning patterns of ministerial advisers when engaged in processes of policy formulation and how can differential learning patterns be explained? This study is based on online survey data collected in 2018-2019, from ministerial advisers working for two Belgian governments: the Walloon Region and the Wallonia-Brussels Federation Governments (n=107, response rate=64%). Statistical analyses were performed using multiple linear and tobit regression techniques. This research shows that, despite remaining political partisan and thus interested actors, ministerial advisers do learn about ...