Autonomy and authority are often seen as opposites. In this essay, I argue that autonomy should rather be seen as a domain-specific form of (practical) authority and that this view helps to identify conditions for the autonomy of individuals. To this end, I will first show parallels between the functioning of the two terms AUTONOMY and AUTHORITY and then work out what requirements this places on a conception of personal autonomy. I will then show that the difficulties faced by some internalist and externalist conceptions of autonomy originate in the fact that both approaches have a false picture of the basis on which the form of practical authority characteristic of autonomy rests. Finally, I will present a conception in which this foundation is constituted by a person`s maturity, defensibility and participation: According to this, a person is autonomous to the extent that he or she can manage his or her own affairs, defend himself or herself against outside interference and have a say in communal affairs.