The main tenet of this paper is that human communication is first and foremost a matter of negotiating commitments, rather than one of conveying intentions, beliefs, and other mental states. Every speech act causes the speaker to become committed to the hearer to act on a propositional content. Hence, commitments are relations between speakers, hearers, and propositions. Their purpose is to enable speakers and hearers to coordinate their actions: communication is coordinated action for action coordination. To illustrate the potential of the approach, commitment-based analyses are offered for a representative sample of speech act types, conversational implicatures, as well as for common ground.