Abstract This study employs the island repair effect on the Left Branch Condition (LBC) to illuminate the derivation of Mandarin sluicing. It utilizes three unique properties of Mandarin island repair related to the LBC involving (i) covert ante- cedents, (ii) contrastive modifiers, and (iii) multiple islands including LBC structures in order to examine two deletion-based analyses of sluicing in the literature. It is shown that these analyses fail to satisfactorily explain the properties discussed. To capture the facts, a pseudosluicing analysis is proposed which claims that sluiced clauses in Mandarin are simply composed of a subject pro, an (optional) copula shi ‘be’, and a wh-in-situ wh-remnant serving as a predicate. The strong redemptive ability of re- pairing LBC effects in Mandarin is attributed to the construal of pro instead of dele- tion. From a typological point of view, among East Asian languages, Mandarin sluices differ from Japanese and Korean sluices in that the pro of the former cannot be interpreted as a concealed cleft structure but instead functions as an implicit subject. Keywords Island repair Left Branch Condition Ellipsis Sluicing Pseudosluicing Empty pronoun Predication 1 Introduction In an attempt to clarify the derivation of Mandarin sluicing, this paper first compares island repair effects of the Left Branch Condition (LBC) in English and in Mandarin Chinese, with a special focus on three differences between these two languages concerning the occurrence of: (i) covert antecedents, (ii) contrastive modifiers, and T.-C. Wei (&) Institute of Taiwanese Cultures and Languages, National Kaohsiung Normal University, No.116, Ho-Ping first Rd., Kaohsiung City 80201, Taiwan e-mail: tingchiwei@nknucc.nknu.edu.tw 123 J East Asian Linguist (2011) 20:255–289 DOI 10.1007/s10831-011-9077-0 Island repair effects of the Left Branch Condition in Mandarin Chinese Ting-Chi Wei Received: 22 September 2009 / Accepted: 18 April 2011 / Published online: 5 July 2011 Ó Springer Science+Business Media B.V. 2011