Del. Code tit. 8, § 605

One or more persons, each of whom is duly licensed or otherwise legally authorized to render the same professional service or any of the qualified related professional services within this State, may organize and become a shareholder or shareholders of a professional corporation for pecuniary profit, under this title, for the sole and specific purpose of rendering the same professional service or qualified related professional services; provided however, a professional corporation shall not be permitted to render qualified related professional services unless at all times at least 1 shareholder is duly licensed or otherwise legally authorized to render each of the component qualified related professional services then comprising the professional corporation.