Modal adjectives pose wide‐ranging questions for the architecture of grammar, because they involve aspects of morphology, syntax and semantics and thus they are a good testing ground to investigate the ways in which these modules interact or how they are constrained, especially in relation to morphosyntactic decomposition, passive and middle voice, types of modality and the notions of stativity and eventivity. They raise further specific questions for syntactic categorization and category change, the nature of non‐verbal semantic modality, the relationship between the syntactic subcategorization properties of the base and those of the modal adjective, or how morphological processes influence the syntactic and semantic properties of adjectives. Some of the main challenges raised by modal adjectives across different languages are reviewed, mainly (i) their modal semantics, in relation to the different root modal interpretations available in the verbal domain, suggesting a neat classification that distinguishes the various dynamic, priority and dispositional/willingness interpretations available; and (ii) their morphosyntactic properties, especially in relation to their (non)‐eventive properties and the typology of ‐
ble
adjectives they give rise to.