This chapter discusses core assumptions in linguistics and language acquisition regarding monolingual and bilingual linguistic knowledge and presents a typology of native speakers that includes heritage speakers. Both layman and academic definitions of a native speaker are discussed, as well as recent research on individual differences in monolingually-raised native speakers related to level of education and other variables that are also relevant for an understanding of heritage speakers. The second introduces the concepts of bilingual and multilingual native speakers and balanced bilingualism, addressing the specific cultural, attitudinal, affective, and sociopolitical factors that affect the acquisition of a heritage language. Heritage speakers’ shift in language dominance with the onset of schooling in the majority language, if not earlier, contributes significantly to reduction in heritage language input and opportunities to use the language at a critical time for language development in childhood. Despite showing obvious changes in some aspects of their grammars, heritage speakers retain native-like abilities in several other aspects, compared to second language learners. The focus of this chapter, and of this book, is more on similarities and differences between heritage speakers and monolingually-raised native speakers than on what heritage speakers and second language learners tend to share.