The acquisition of diminutives in Spanish, facilitated by phonoprosodical, morphological and pragmatic means, becomes more than a simple morphopragmatic device to be acquired. This paper proposes that it provides the child with essential cues for grammatical segmentation, which proves very useful in later stages of language development. To test this hypothesis, an analysis of two longitudinal corpora of Spanish L1 has been carried out. Quantitative considerations included type/token ratio in children and cds across ages and word classes; qualitative considerations included a search for the emergence of the first contrast (mini-paradigms). Both perspectives confirm a pattern of a very rapid development and mastery of diminutive formation. Some other aspects, such as morphophonology, suffix selection and spontaneity versus imitation, are also considered. The paper rounds up with some considerations regarding the semantics and pragmatics of diminutives in Spanish.