This data set includes the supplementary material for the article "The uses of clitic si in Child Italian". All content is documented in the README.md file. Abstract: This paper investigates the different uses of the clitic si in Child Italian. Through a corpus study on spontaneous productions of children aged 1;4-3;4, we check whether all functions of si are realized by children and we give a new perspective from language acquisition to a long-standing debate, namely whether there exists only one type of si or whether there are many different ones. Our results show that Italian children use si productively and adult-like early on, and they produce all its different functions: impersonal, anticausative, true reflexive, and inherent reflexive – although at different rates. We claim that our results support the one si approaches, and the difference in the frequencies of si functions reflects the structural complexity of some structures.