Sign languages offer a unique and informative perspective on the question of the origin of phonological and phonetic features. Here I review research showing that signs are comprised of distinctive features which can be discretely listed and which are organized hierarchically. In these ways sign language feature systems are comparable to those of spoken language. However, the inventory of features and aspects of their organization, while similar across sign languages, are completely unlike those of spoken languages, calling into question claims about innateness of features for either modality. Studies of a young village sign language, Al-Sayyid Bedouin Sign Language (ABSL), demonstrate that phonological structuring is not in evidence at the outset, but rather self-organizes gradually (Sandler et al 2011). However, our new research shows that signature phonetic features of ABSL already can be detected when ABSL signers use signs from Israeli Sign Language. This ABSL ‘accent’ points to the existence of phonetic features that may not be distinctive in any sign language but can distinguish one sign language from another, even at an early stage in the history of a language. Taken together, the findings suggest that physiological, cognitive, and social factors are at play in the emergence of phonetic and phonological features.