What is Leucippus and Democritus’ theory of the beginning of life? How, if at all, did Leucippus and Democritus distinguish different kinds of living things? These questions are challenging in part because these Atomists claim that all living beings – including plants – have a share of reason and understanding. We answer these questions by examining the extant evidence concerning their views on embryology, the soul and respiration, and sense perception, thereby giving an overview of life and lifeforms in early Greek atomism. We show, first, that the generation of all living beings happens through the combining of miniature copies of their parents’ atomic structures. Second, we argue that the Atomists take respiration to mark the beginning of life. Yet they do not consider respiration nor being ensouled to distinguish humans, animals, and plants from each other. Finally, because Leucippus and Democritus make little distinction between sense perception and thought, these too cannot sharply distinguish between different kinds of living beings. We conclude that Leucippus and Democritus advocated a less anthropocentric and more holistic view of the cosmos.