Concepts and assumptions of self-in-relation theory of women's development, as proposed by feminist scholars at the Stone Center in Wellesley, Massachusetts, are applied in this article. This theory was used as a framework to guide staff development and mentorship roles of advanced practice nurses. How the theory served to direct these roles and assisted in development of a professional practice model is discussed. Exemplars from the author's practices and professional practice outcomes after 2 years of theory implementation are presented.