This volume includes twelve papers selected from the Twentieth Annual Symposium on Arabic Linguistics, held in 2006 at Western Michigan University, Kalamazoo. The papers in this volume address a broad range of theoretical issues pertaining to Arabic, particularly in the areas of phonology, morphology, syntax, pragmatics, computational linguistics, and psycholinguistics. These contributions represent the emerging trend of interface research, where linguistic phenomena are investigated using the techniques, methodologies, and theoretical frameworks of different academic fields.