This paper attempts to predict diachronic change in the restricted domain of Italo-Romance first person plural present indicative allomorphs, starting from the reconstructed Proto-Italo-Romance forms -amo, -emo, -imo, preserved in several dialects to this day (with
corresponding subjunctives -emo, -iamo, -iamo). The predictions, or rather retrodictions (to be differentiated below) are based on the theory of Natural Morphology (NM). Morphology-initiated changes lead to 64 logically conceivable distributions in the earlier and present
Italo-Romance dialects. The retrodictions are meant to account for the identity of attested distributions with possible (‘legal’) distributions, for unattested impossible (‘illegal’) distributions and for two accidental gaps in distributions. Moreover, we try to predict
why certain attested distributions are more probable and therefore more frequent than others and introduce a new method of empirically testing such probability retrodictions.