This Element presents a Cognitive Grammar (CG) approach to a range of signed language grammatical phenomena. It begins with a background on the history of sign linguistics, focusing on what was a widely held belief that signs are simply gestures. The first section traces the modern linguistic examination of signed languages, focusing on Stokoe and his demonstration that these languages exhibit phonology and duality of patterning. Next, we present some fundamental principles that are foundational for cognitive linguistics and sign linguistics. In a section on Cognitive Grammar, we present a brief overview of CG principles, constructs, and models. Section 4 presents extensive analyses of signed language constructions applying CG, including nominal grounding; the concepts of Place and placing; a CG approach to 'agreement' constructions in signed languages; reported dialogue; grammatical modality; and the grammatical meaning of facial displays. The final section examines the controversial role of gesture in grammatical constructions.