First part of a two-part article on Art. 1 (Persons covered) of the OECD Model tax Convention. In this part is demonstrated that the way in which Art. 1 developed shows that it is a mere corollary to the principles underlying the substantive provisions of the OECD Model. Art. 1, however, is not an omissible part of those principles. Shows that Art. 1 is a significant and essential part of the OECD Model.