For several decades, there has been an interest in understanding how Emotion Comprehension (EC) and Theory of Mind (ToM) are related during the preschool years. In addition, the links between language and ToM and language and EC have been studied. Although prior work shows the influence of language on ToM and EC, the relationships among these three variables have not been sufficiently studied until now. The aim of this short research report is to test the relations among these three skills during a critical period of development, using a wide range of ToM, EC, and language components. To do so, the authors evaluated EC through six components of the TEC (Pons & Harris, 2000) and ToM through the seven tasks of the Wellman and Liu Theory of Mind Scale (2004). Language was evaluated by the PLON-R, a Spanish test of language development that includes four different dimensions. Results show that at four years of age, the relationship between ToM and EC is mediated by language, suggesting that language is a key process in the development of socio-emotional competence. The results suggest the need to work on EC and ToM through language from early ages. Through their discourse, adults influence the child's comprehension of mental and emotional realities and model their narrative skills. These narrative skills allow the child to construct coherent and structured explanatory frameworks, making explicit what in most cases is implicit.