This grammar is a first detailed description of Qaqet, a non-Austronesian language spoken in the mountainous interior of East New Britain Province, Papua New Guinea. Qaqet belongs to the small Baining language family (comprising six languages), but its wider genetic affiliations remain unclear. It is included among the geographically-defined East Papuan languages. The grammar presents a synchronic description of the language. From a language family perspective, the Baining languages are structurally fairly similar, but there are considerable differences in detail that point to different language-internal developments and grammaticalization paths. From an East Papuan and areal perspective, Qaqet exhibits both typical East Papuan features (e.g., nominal classification, possessor/possessed order, highly compositional lexicon) as well as areal features (e.g., AVO SV constituent order, articles and determiners, prepositions). The description is based on primary data collected during fieldwork (from 2011 onwards), including both natural and elicited data. The description thereby provides new analyses and insights that are relevant to our understanding of the genetic and areal relationships in this region.