Abstract. This paper deals with the phenomenon of Focus Fronting and addresses the vexed question of its optional realization. A novel path for explanation is thus proposed, based on intervention effects and, in particular, on Superiority at the External Merge of arguments in the vP shell. To this purpose, an original experimental test has been designed for a systematic comparison between Subject and Object Focus in corrective replies, from which evidence is provided for a significant difference between transitive, unaccusative and unergative verbs.

Furthermore, a gradient approach is advocated for intervention effects, based on the combination of different features. The incidence of alternative Focus constructions is also taken into consideration (i.e., postverbal Subject, cleft sentences and passives) and relevant asymmetries are treated in a comprehensive account.

· This paper is part of a joint work with Giorgio Carella & Marco Casentini, to be published in: Balsemin, Tommaso, Irene Caloi, Jacopo Garzonio, Nicolas Lamoure, Francesco Pinzin & Emanuela Sanfelici (eds.), Festschrift in honor of Cecilia Poletto’s 60^th Birthday. Quaderni di Lacoro ASIt, 23.