The authors agree that the surname derives from the occupational name pastore, “shepherd,” referring to one who raises and guards livestock. E. De Felice specifies that it became a surname from the name and nickname Pastore, already documented in the 13th century in the Latinised forms Pastor, Pastorius and Pastorinus.

As to geographic distribution, De Felice notes that the form Pastore predominates in Campania and Liguria, while Pastoressa is concentrated in Apulia and Pastrello appears in the Venice area. F. Miranda broadens this picture and indicates that the surname is spread across much of Italy, with a greater presence in Apulia and Campania, and with areas of significant concentration in Piedmont and Lombardy. It also appears, more dispersed, in Lazio, Veneto, Basilicata and other regions.

Miranda adds that in Sicily the surname is present in almost every province, with a greater concentration in the Catania area —in localities such as Palagonia, Catania and Aci Catena—, the Trapani area —Trapani, Mazara del Vallo and Erice—, the Palermo area —Palermo, Balestrate, Isnello and Carini— and the Messina area —Milazzo, Giardini Naxos, Messina and Lipari—. In the Enna area it is recorded in Agira, Nissoria and Regalbuto.