A corporate portal supports a community of users on cohesively managing a shared set of resources. Such management should also include social tagging, i.e. the practice of collaboratively creating and managing tags to annotate and categorize content. This task involves to know both what to tag (hence, the rendering of the resource content) and how to tag (i.e. the tagging functionality itself). Traditionally both efforts are accomplished by the same application (Flickr is a case in point). However, portals decouple these endeavours. Tagging functionality is up to the portal, but content rendering can be outsourced to thirdparty applications: the portlets. Portlets are Web applications that transparently render their markup through a portal. The portal is a mere conduit for the portlet markup, being unaware of what this markup conveys. This work addresses how to make portlets tagging-aware, i.e. portlets that can be seamlessly plugged into the portal tagging infrastructure. The main cha...