DescriptionThis thesis is concerned with sluicing, the ellipsis of TP in a Wh-question leaving a Wh- phrase “remnant” overt. Sluicing is subject to an identity condition that must hold between the sluiced question and its antecedent. There is currently no consensus on whether this condition should be characterized as syntactic or semantic in nature, or whether a hybrid condition that makes reference to both semantic and syntactic identity is needed (Merchant 2005, Chung 2013, Barker 2013). I provide a new identity condition that captures extant syntactic generalizations while allowing for enough wiggle room to let in detectible mismatches between the antecedent and sluice. The identity condition I propose is “split” between two sub-conditions, one that pertains to the relationship between the sluiced Wh-phrase and its correlate in the antecedent (the Remnant Condition), and one that pertains to the sluiced question as a whole (the Sluice Condition). The Split Identity hypothesis counts as a hybrid identity condition. The Remnant Condition is novel, and requires that the remnant have a syntactic correlate in the antecedent with which it matches semantically. Split Identity is shown to capture the data motivating extant syntactic generalizations. The Sluice Condition requires that the sluiced question and the Question under Discussion (QuD) that the antecedent makes salient seek the same answers, and is an implementation of QuD-based approaches to the semantic condition on sluicing, such as recently proposed in AnderBois 2011. The Split identity condition also lets in “pseudosluices” alongside isomorphic sluices, where the sluiced question is a cleft or a copular question while the antecedent is not. Pseudosluicing has often been proposed as a last resort mechanism, only available when an isomorphic structure is independently ruled out (Rodrigues et al. 2009, Vicente 2008, van Craenenbroeck 2010). I defend a view where pseudosluicing is not a special case of sluicing, so that the identity condition should not distinguish between copular and non- copular clauses in the determination of identity. Split Identity achieves this in making no reference to the syntactic content of the ellipsis site.