This study investigates the reasons behind the decision to send children aged under three to ECEC (Early Childhood Education and Care) and the causes that may explain why some families send their child to ECEC once they reach the age of two while others decide to do so at an earlier age. To answer the first question posed a probit model is used, while to answer the second query a Heckprobit model is estimated to take into account possible selection bias. The data for this study was taken from an unpublished database compiled by the Spanish National Institute for Educational Evaluation, which gathers information from 1.166 children schooled in the Infant Education stage. The results of our estimations show that the decision to enroll children under three in ECEC services depends fundamentally on the sociodemographic characteristics of the mother (educational level, employment situation and age), on household size (if it is a large family) and on the availability of ECEC services in the area in which the child lives. Our study has also shown that the only variable regarding factors that explain the differences in the age of access to ECEC services, two or under two, is the importance that parents place on their children developing empathy towards others. On the basis of our results, the study offers recommendations aimed at the progressive universalization of this initial educational stage.