Pashto/Pushto/Pukhto is a group of varieties used by as many as 30 million people in Afghanistan and Pakistan, yet a grammar describing these varieties collectively has not been published. The CASL Pashto grammar originates from extensive use of both primary and secondary materials. It attends to features of both spoken and written forms of Pashto and exemplifies the latter generously with naturally-occurring sentences. Detailed descriptions are provided of the phonology and orthography and of the inflectional and derivational morphology applied to all major word classes, with special attention to the complex morphology of verb formation and descriptions of the multiple pronominal systems. Notes on some of the prominent syntactic constructions are provided as a descriptive basis for learners of Pashto and for those interested in syntactic properties characteristic of South Asian languages. For the first time, the highly distinctive Middle dialects, including Waziri, receive attention next to the other major dialect groups. A formal grammar focusing on the morphology is an available companion work.