Infants undergo a series of dynamic changes during the first year of their life, starting at nearly complete dependence upon others for all functions, culminating with the ability to self-transport and rudimentarily converse around the age of 12 months. Previous research indicates an interaction between walking and expressive and receptive language development. Given that phonology underlies expressive language production, in this study we are exploring potential relationships between locomotion and phonological development by examining phonetic inventories of age-matched peers who are walking or crawling. We are transcribing canonical utterances from high-volubility samples taken from daylong home audio recordings of 18 English-learning infants. Various phonetic features of the infants’ productions are compared across locomotor groups, in search of an interaction between phonological and locomotor development. This work is informing our understanding of the mechanisms through which locomotor and language development are interrelated.