In this article we try to determine the diachronic origin of a few sentential particles attested in some North-Eastern Italian dialects on the basis of their syntactic properties. The particles we consider are associated with specific clause types and can only appear in matrix non-declarative clauses; they generally occur in sentence-final position, and only some of them can follow the wh-item in an interrogative clause. They display the typical properties of X°-elements, and can therefore be analysed as functional heads of the CP layer; we present an analysis exploiting movement of the wh-item or of the whole clause to the specifier corresponding to the head occupied by the particle. The different distribution that characterizes the two main types of particles seems to depend on whether they derive etymologically from pronouns or from adverbs; the new properties developed in the grammaticalization process suggest that when an element is reanalysed as a functional category, it can further acquire the value of functional projections merged close to it in the structure.