Sluicing – the elliptical construction in which all of a constituent question goes missing except for the interrogative phrase – is commonly analyzed as involving movement of the interrogative phrase to Spec-CP followed by deletion of TP (Ross 1969, Merchant 2001). In this paper, I examine how well the movement-plus-deletion analysis extends to Farsi, a wh-in situ language that, surprisingly, has a sluicing construction nearly identical to its English counterpart. I argue that the interrogative phrase in Farsi sluicing escapes deletion not by wh-movement as in English but by a type of focus movement. This operation, which normally applies very generally and is optional, is restricted in sluicing contexts in two ways: (i) it is obligatory, and (ii) it only applies to interrogative phrases. I propose a formal implementation that integrates these two properties into the licensing requirement on deletion, advancing the current understanding of the syntax of sluicing.