Commitment is a notion widely invoked in speech-act theory, in studies on modality and in dialogue modelling, but it has never been the central topic of a monograph or a collective volume in linguistics. This volume is the very first to bring together researchers from different linguistic traditions and request them to focus on the notion. All the contributions presented here use commitment as a key concept in accounting for a broad range of linguistic phenomena in various languages, from illocutionary acts like assertions and questions to modal expressions, through sentence-types, finite subordinate clauses, concessive markers, tense markers, and even text-types and genres. Each contributor takes pains to explicate his/her understanding of the term commitment, thus making interesting comparisons possible across theoretical boundaries. Some authors also point out potential drawbacks of the notion and argue for replacing or supplementing it with a related concept of involvement.