Linguistic imitation is not mere repetition but a foundational mechanism of language use. We imitate every time we reuse and adapt someone's ways of communicating. This book redefines imitation as the creative engine of interaction, showing how language evolves through engagement with what others say and do. It discusses dialogic resonance – speakers' reuse and recombination of communicative constructions – as a unifying framework bridging pragmatics and construction grammar. Combining evidence from first and second language acquisition, intercultural communication, language change and neurodiverse interaction, the book highlights imitation's role in defining four pillars of social cognition: conformity, engagement, categorisation and innovation. Combining qualitative case studies with corpus-based and statistical analyses, it provides a multimodal framework for studying how humans imitate others to communicate. It is essential reading for scholars and students of linguistics, psychology, education and sociology, and anyone interested in how language emerges and develops through the readaptation of others' communicative behaviours.