The cognitive theory of mental spaces and conceptual integration (MSCI) is a twenty-year-old, cross-disciplinary enterprise that presently unfolds in academic circles on many levels of reflection and research. One important area of inquiry where MSCI can be of immediate use is in the pragmatics of written and spoken discourse and interaction. At the same time, empirical insights from the fields of interaction and discourse provide a necessary fundament for the development of the cognitive theories of discourse. This collection of seven chapters and three commentaries aims at evaluating and developing MSCI as a theory of meaning construction in discourse and interaction. MSCI will benefit greatly not only from empirical support but also from clearer refinement of its methodology and philosophical foundations.