The study presented in this paper examines the context-dependence and dialogue functions of the contrastive markers of Italian <i>ma</i> (but), <i>invece</i> (instead), <i>mentre</i> (while) and <i>però</i> (nevertheless) within task-oriented dialogues. Corpus data evidence their sensitivity to a acognitive interpersonal context, conceived as a <i>common ground</i>. Such a cognitive state – shared by co-participants through the coordinative process of grounding – interacts with the global dialogue structure, which is cognitively shaped by “meta-negotiating” and grounding the dialogue topic. Locally, the relation between the current dialogue structural units and the global dialogue topic is said to be specified by information structure, in particular intra-utterance <i>themes</i>. It is argued that contrastive markers re-orient the co-participants’ cognitive states towards grounding ungrounded topical aspects to be meta-negotiated. They offer a collaborative context-updating strategy, tracking the status of common ground during dialogue topic management.