Sluice resolution in English is the problemof finding antecedents of wh-fronted ellipses.Previous work has relied on handcraftedfeatures over syntax trees that scalepoorly to other languages and domains;in particular, to dialogue, which is one ofthe most interesting applications of sluiceresolution. Syntactic information is arguablyimportant for sluice resolution, butwe show that multi-task learning with partialparsing as auxiliary tasks effectivelycloses the gap and buys us an additional9% error reduction over previous work.Since we are not directly relying on featuresfrom partial parsers, our system ismore robust to domain shifts, giving a26% error reduction on embedded sluicesin dialogue.