Based on ethnographic research in Athens, this paper argues that in vitro fertilization (IVF) in urban Greece does not so much make explicit the social construction of nature, as has been argued of the US and UK, but is accommodated into a prior understanding of nature as socially realized. Calling upon an ethic of maternal sacrifice, Athenian women see themselves taking charge of a natural process, often correcting damage done to them by nature. A sense that adults should produce children in order to realize their natures and be completed as women and men also poses particular, and gendered, ethical questions of fertility technologies: is this a proper way of realizing nature? While those who successfully use IVF depict assisted conception as a natural and proper way of reproduction. some fear that others will view their child as abnormal. Contests over normal reproduction are articulated to a tradition/modernity dichotomy which Athenians discuss through an idiom of maturity. Believing that Greek society is not always mature enough to understand how natural IVF really is, couples turning to IVF follow one of the two strategies: to educate others or to completely hide it. Both groups want to guard against a view of IVF in the terms of this volume- as a kind of reproduction gone awry. Español