This study evaluates 39 different phonetic inventories of 16 Spanish-speaking children (ages 0;11 to 5;1) in terms of hierarchical complexity. Phonetic featural differences are considered in order to evaluate the proposed implicational hierarchy of Dinnsen et al.’s phonetic inventory typology for English. The children’s phonetic inventories are examined independently and in relation to one another. Five hierarchical complexity levels are proposed, similar to those of English and other languages, although with some language-specific differences. These findings have implications for theoretical assumptions about the universality of phonetic inventory development, and for remediation of Spanish-speaking children with phonological impairments.