This study explores the protolinguistic development from birth of one child in a bilingual context. Protolinguistic data, non-verbal and socio-cultural influences were recorded using field notes, audio and video recordings. The data collection techniques were selected in order to develop upon and avoid criticisms levelled at similar, monolinguistic studies. Protolinguistic expressions were coded using the International Phonetic Alphabet. They were then analysed and classified according to linguistic function following models set by Halliday (1975) and Painter (1984). Central to the data analysis were the credibility checks undertaken. Each linguistic expression was subjected to “member checking” (Cuba and Lincoln, 1985) by a team of English and Spanish speakers. Resultant data reflects a systematic development of linguistic options within six protolinguistic functions, strongly supporting the general sequential development as outlined by Halliday (1975) and Painter (1984). The development of lexical items from both the mother's tongue (Spanish) and the father's tongue (English) are identified and compared with these monolingual studies. Relationships were also identified between protolinguistic expressions and the language demonstrations provided by the parents.