Texas A&M University at College Station (A&M) and the University of Texas at Arlington (UTA) employed portfolio assessment in their field-based principal preparation programs using the 21 performance domains of the National Policy Board for Educational Administration. In a joint venture with the Bryan Independent School District, selected A&M students began the school year in their regular positions as teachers, but were given considerable latitude by their schools to become involved in field-based leadership experiences throughout the administrative internship program. In the "Educational Leadership UTA" Program, organized with the Dallas/Fort Worth public schools, interns left their teaching positions for one full calendar year, and engaged in three 12-week field-based internships, one each in elementary, middle, and high schools. Students from both universities maintained a log of daily activities during their field projects, and collected records, documents, and other artifacts that attested to the scope and quality of their performance. These sources, along with course papers, texts, and other relevant materials, became their portfolios. Results of the study indicated that the use of portfolio assessment in measuring the professional development of administrative interns gave them a focus for developing the skills most commonly identified as essential to campus-based administrative leadership success. Students reported that having the 21 performance dimensions around which to build their portfolios helped them move from the abstract idea of portfolio assessment to the concrete reality of exactly what to include to make their portfolio evaluation authentic and professionally meaningful. (ND)