I examine the set of environments in which KA-type quantifier particles appear crosslinguistically. These environments include interrogatives, disjunctions, indefinites, all of which arguably involve elements with Hamblin-type ‘alternative’ semantic values. I show that if KA-particles are assigned a uniform denotation as variables over choice functions we can account for their appearance in what otherwise appears to be a set of heterogeneous environments. Crosslinguistic and diachronic variation in the distribution of Q-particles – including, in some cases, the appearance of multiple morphologically-distinct Q-particles in different contexts – can be handled largely in terms of differing formal morphosyntactic features and/or pragmatic components of specific KA-particles. This study focuses on tracking the evolution of KA-type particles in the history of Sinhala, with comparison to other languages of the Indian subcontinent (including Malayalam and Tamil) as well as to Japanese, Tlingit, and English.