This study explores the impact of bimodal bilingual parental input on the communication and language development of a young deaf child. The participants in this case study were a severe-to-profoundly deaf boy and his hearing parents, who were enrolled in a bilingual (English and Australian Sign Language) homebased early intervention programme. The parents typified the challenges faced by hearing parents of deaf children seeking to provide a bimodal language environment for their deaf child. Data were collected over 20 months when the boy was aged between 23 and 42 months. The parents' level of Auslan proficiency, bilingual practice, and sensitivity to their son's communication needs were measured. Findings indicated that although communication and language outcomes were delayed compared with hearing peers, English and Auslan vocabulary growth over time was strongly correlated with the parents' sensitivity to his communication needs. Findings also indicated that there were several child-led changes in language modality preferences throughout the study.