Technologies that support communication and models used in the development of communications need good underlying theories. One theory suggested as a base for design is speech act theory. Both communication support tools and modelling notations informed by speech act theory have been proposed. Speech act theory forms no unified, single theory, but actually houses several variants for dealing with semantics, pragmatics, and social context of communications. They all have one common feature: they assume that language is not merely a means of describing but also a means for doing things. In this paper we present an overview of speech act theories and their uses in information systems research. Our focus is on examining success of speech acts and commitment negotiations. We suggest a new model of commitment making that combines different speech act theories and their criticisms. It can be used in developing more adequate models of information systems and in highlighting requirements for flexible coordination support tools. The creation of shared understanding and agreement as well as the representation of context are emphasised.