The main goal of the present paper is twofold: on the one hand, to highlight the patterns of variation among the existential constructions found in Italo-Romance; on the other, to examine the observed microvariation in a comparative perspective in order to identify common properties and general tendencies. Starting from a description of the variation concerning the primary components of existentials, I demonstrate that, irrespective of the superficial morphosyntactic variation attested, all Italo-Romance existential constructions share a fundamental property: their distinguishing features can all be viewed as the reflection of the persistence of formal properties continuing or overlapping with a source construction. This construction is either the locative predication, when be is selected, or the possessive structure, when the existential copula is have. The pivot of the existential construction therefore shows typical properties of arguments, but is however subject to a high degree of instability and variation because it has been semantically reanalysed as the predicate of an abstract contextual domain serving as the argument of the existential proposition. This mismatch between the syntactic and the semantic characteristics of existential structures contributes to the microvariation encountered.