Henniker Sign Language was a village sign language of 19th-century Henniker, New Hampshire and surrounding villages in the US. It was one of the three local languages which formed the basis of American Sign Language. Although the number of students from Henniker were fewer than speakers of the more famous Martha's Vineyard Sign Language, deafness in Henniker was genetically dominant, and Henniker SL was therefore likely to have been better developed than MVSL.