This thesis examines a series of related semantic phenomena in the interaction of modality and tense. It is composed of four self-contained academic articles (each one corresponding to one of the chapters between Chapters 2 and 5). The first two articles are mainly focused on English future constructions and their illocutions, while the last two constitute semantic studies in Mapudungun, an indigenous language of the Araucanian family. The general framework adopted throughout the thesis is that of truth-conditional semantics, although the opening article is more pragmatically-driven within a dynamic account. Chapters 2 and 3 defend the general view that future statements should not be reduced to the predictive. They achieve this by different means: while Chapter 2 adopts a pragmatic perspective, examining a series of normative and dynamic aspects of futureoriented illocutions, Chapter 3 is specifically concerned with the semantics of English constructions used to express future obligations. The articles share a dynamic view on meaning (and human communication more generally), although the technical implementation of their corresponding analyses substantially varies: while Chapter 2 develops a conceptual and partly philosophical examination of future illocutions, Chapter 3 builds on a compositional analysis of the combined expression will have to. Chapters 4 and 5 develop a systematic account of certain modal expressions in Mapudungun. Based on a set of data obtained in recent fieldwork conducted in Chile, I offer an account of some fairly unexplored aspects in Mapudungun expressions of obligations (Chapter 4) and desires (Chapter 5). Two theoretical issues are examined: (i) the future-orientation of Mapudungun circumstantial modals and bouletic predicates, and (ii) their morphological transparency. The former of these issues relates to the semantic contribution of the future morpheme -a- in the nominalised complement of deontic and bouletic constructions; and the latter to the one brought about by the counterfactual morpheme -fu- in the same type of constructions. The hypotheses defended in each of the articles allow us to compare Mapudungun expressions of obligations and desires to what is reported of other languages in and outside the Americas.