In this research, we analyze the development of prosodic features to organize information and highlight sentence focus in semi-spontaneous narratives of children between 4 and 10 years old. We conducted experimental research with three children from Santiago de Chile aged 5, 7, and 9 years. We identified representative features of different stages of language development and, thus, proposed a hypothesis regarding the development of prosodic codification of the focus. We acoustically analyzed the segmented clauses for pitch alignment, pitch excrusion, and vowel duration with the nuclear focus stress. As to the prosodic coding of focus, specifically regarding pitch and duration, this study shows emerging features of a phonological adult model of accent assignment and alignment of the tonal peak, but with phonetic variation among children of different ages, specifically regarding pitch high and duration of the tonic syllable. These findings are new within the framework of the study of language development in Spanish and shed light on the phonetic development of prosody.