The increase of syntactic complexity evidences the linguistic development of children. The use of certain language measures makes it possible to account for this process, which has been corroborated in Spanish-speaking preschool children and children in late stages of language development. This work proposes to explore this development by contrasting a group of Chilean children with typical development who attend preschool with a group of first grade school children. The measures included primary and secondary indices of complexity, and were obtained from narrative retellings produced by the children. Results show that not all the indices increase when the two groups are compared. Only a primary index of clausular density within the complex sentences increases and the number of noun subordinates, particularly in the narrative stages of presentation and ending; in parallel, the number of adverbial subordinates in the final phase decreases. These results show that, although there is an increase in some measures of complexity in contrasting groups, the development of these skills does not present a constant rhythm in all dimensions, which may be due to discursive factors or to the process of linguistic development itself.