The present longitudinal case study was designed to investigate the possibility that a traumatic brain injury (TBI) occurring during the second year of life, while significant lexical and grammatical competencies are emerging, could have an impact on subsequent language development. Thus, the language development of a very young girl (BL) who suffered a TBI at the age of 17 months was monitored for 6 months following the injury. Different procedures were used to measure her lexical and grammatical development: monthly parental checklists, free-play sessions and word-learning tasks. BL's results were compared with two control groups (n = 5 and 9) matched for age and gender. Overall, the results are consistent with the classical view of acquired language disorders in children: despite an initial decrease in the use of her premorbid vocabulary, BL showed no durable significant impairment on any measure of lexical or grammatical development.