This chapter reflects on Maria Lyra’s holistic-dialogical framework and its implications for developmental psychology, especially regarding the emergence of the self. Drawing on Lyra and Rossetti-Ferreira’s (1987) foundational work, three interrelated principles are identified as being central to this approach: the dialogical unit of analysis, development as differentiation, and the multimodal and socioculturally embedded nature of interaction. Lyra’s contribution is situated within a broader historical and theoretical context—linking it to Vygotsky, Werner, Bakhtin, and Humboldt. From this theoretical basis, it is argued that early mother–infant interactions constitute a dynamic, co-constructed unit of development rather than an exchange between separate individuals. The chapter emphasizes how the self emerges through dialogical processes involving mutual transformation, abbreviation of interactional histories, and sociocultural embeddedness. By integrating theoretical insights with empirical studies, the chapter advances a relational and processual view of self-development that challenges mechanistic and individualistic models in mainstream psychology.