This paper explores the crucial role of relational emotions in children’s language learning and argues for an intersubjective theory of language development. To demonstrate the need for this approach, first a review of different classical theories of language acquisition as well as of more recent emergentist approaches is given. From this it is obvious that in all discussions about the opposition or the interplay between nature, nurture and culture and therefore the primary motives for children’s language development, no prominent theory explicitly focuses on the importance of emotions in language or in prelinguistic and linguistic development. Only in the interactionist and psychoanalytic models do we find implicit concepts about affective influences on language constitution. In response to this lack, evidence is given for the semiogenetic power of emotions from recent semiolinguistic and neuropsychological research, both of which employ the concept of ‘intersubjectivity’. The findings from these two fields of investigation are summarized in an application to children’s semiolinguistic development. Four major milestones of affect and meaning attunement in the child’s trajectory from emotional regulation of interpersonal contact and cooperation to cognitive mastery of experience in the intersubjective construction of signs are described. The paper concludes with an outline of the concept of ‘Relational Language Therapy’ – a therapeutic approach to language learning, which views as central the emotion-based influence of a ‘Significant Other’ in both parental and professional support of children’s semiolinguistic development. Finally as a vision for future theorizing, these paradigm shifts are taken to pave the way for fully incorporating the concept of intersubjectivity into linguistic theory and its various fields of application.