This chapter describes challenges of proposing a different understanding of a well-known phenomenon, imitation (and its development in young children). The first challenge was to study imitation as a shared motor activity in a two-person perspective, instead of as a solitary tool for learning or forming mental images. A related challenge was to analyse imitation as a multifaceted phenomenon involving a hierarchy of mechanisms according to what, when, and how you imitate. This led to challenging the assumption that people with autism spectrum disorder cannot imitate and claiming, “Yes, they can!” Finally, hyperscanning two brains during synchronic imitation allows assessment of interbrain synchronization. From this an ultimate challenge emerges: to see imitation in its substitutive role as a multiplier of symbolic creations in a two-person generative mind. More generally, I explain how such a perspective builds on the philosophical framework of Henri Wallon that I encountered early in my career and that stood in opposition to the then-prevailing Piagetian paradigm.