The role of context is investigated in natural-language communication by differentiating between cognitive, linguistic and social contexts. It is firmly anchored to a dialogue framework and based on a relational conception of context as structured and interactionally organised. It adopts bottom-up and top-down perspectives and argues for natural-language communication as a dialogical, cooperative and collaborative endeavour, in which local meaning is negotiated in context. In the case of an acceptance, an utterance and its presuppositions are allocated to the dialogue common ground and assigned the status of co-suppositions. In the case of a non-acceptance, a negotiation-of-validity sequence is initiated. The adaptation of both micro and macro perspectives requires a differentiation between unilateral speech acts and collective dialogue acts, individual I-intentions and collective WE-intentions, individual presuppositions and collective co-suppositions, and individual sensemaking and collective coherence.