This paper addresses the interface between syntax and information structure by interpreting focus under negation. To this end, data will be examined from the Arabic negative marker laysa, which exhibits interesting focus features that broaden our knowledge of syntactic and semantic aspects of negation and deepen our understanding of what information structural effects play a role at the interface. Focus typology can be expressed by laysa in its two major types, namely the information focus and contrastive focus, resulting in three different ways in which negation and focus can interact at the Syntax-Information Structure Interface. These ways I would like to express my deepest gratitude to Qassim University for supporting this work. I am very grateful to Anders Holmberg and Abdelkader Fassi Fehri for many interesting discussions we have had about syntax in general and Minimalism in particular. Special thanks are forwarded to Ahmed Alkuraydis for helping me with the bibliographies. I am solely responsible for any mistakes or inadequacy.Nasser Al-Horais Arabic Language Department, Qassim University P.O.Box 6611, Buraidah 51425, Saudi Arabia Email: nasser.alhorais@gmail.com Received 11 February, 2017; Revised 13 March, 2017; Accepted 17 March, 2017 2 On Negation and Focus in Standard Arabic: An Interface-based Approach are of three different readings of focus (wide, bound, and free). Each of these foci involves a different derivation which reflects how the autonomous notions of information structure -topic, focus, and contrast -interact in systematic ways with syntax as shown by the proposed minimalist analysis for each type.