This study focuses on the passage from speech perception to the morphophonological representation of functional elements, verbal affixes in particular, and on the early parsing of linguistic utterances in language acquisition. A psycholinguistic perspective to language acquisition is adopted together with a minimalist conception of language (Corrêa, 2006). The working hypothesis is that closed class elements are distinctively perceived by children initially at a phonetic/phonological level and subsequently at a morphophonological one. Their representation as functional elements at a later stage contributes to the parsing of linguistic utterances. An analysis of a set of tales for children has demonstrated that determiners and verbal affixes occur at the edges of phonological phrases and phonetic properties such as the accent may contribute to their early perception by children. Three experiments were conducted, the first two in Head-turn Paradigm and the latter in the Intermodal Preferential Looking paradigm. Experiment 1 aimed at assessing 9-15 month infants sensibility to phonetic distinctions in the linguistic stimulus, which affect the syllabic pattern of the language (Brazilian Portuguese), independently of the morphological context in which they occur (verbal affixes and nominal roots). Experiment 2 aimed at verifying whether these morphological contexts affect infants perception of phonetic alterations that do not affect the phonological pattern of the language. The perception of such distinctions in the verbal affixes, but not in the nominal roots, was considered to indicate sensibility to the morphophonological patterns of these closed class elements. The third experiment aimed at verifying the extent to which children by the age of 21 months would rely on functional information in the parsing of linguistic utterances, thereby ascribing different categorical features to homophonous words (nouns and verbs). The results of Experiment 1 suggest that 9-15 month infants do perceive phonetic alterations that affect the syllabic pattern of language, regardless of the morphological context in which they occur. The results of the Experiment 2 suggest that infants are sensitive to phonetic alterations that do not affect the syllabic pattern of the language by the end of their first year of life (9-12 months). The results of Experiment 3 suggest that take into account different syntactic projections of the determiner in ascribing homophonous words to different classes (noun and verb). These results also indicate that verbs are analyzed as such regardless of the type of morphological affix they present (marked or unmarked for Tense). However, tensed marked forms seem to add processing costs in the accomplishment of the task. These results are compatible with the hypotheses that guided the present thesis and enable a theory of language acquisition to reconstruct the passage from the phonetic perception of the linguistic stimulus to the morphophonological representation of closed class elements (verbal affixes) and from this level of representation to children s reliance on functional elements in the parsing of linguistic utterances.