Central Park East Secondary School (New York) is a school committed to authentic and learner-centered education. The school has developed an approach to assessing student performance that is active, authentic, and learner-centered. Students in the school's Senior Institute, a division comparable to the traditional grades 11 and 12, prepare 14 portfolio requirements and present 7 of them orally as graduation requirements. These portfolios, along with a common core of coursework and community internships, make up the Senior Institute curriculum. Portfolio requirements include: (1) postgraduate plan; (2) autobiography; (3) school and community service and internships; (4) ethics and social issues; (5) fine arts and aesthetics; (6) mass media; (7) practical skills; (8) geography; (9) second or dual language; (10) science and technology; (11) mathematics; (12) literature; (13) history; and (14) physical challenge. A more extensive final senior project, which may be an exploration of one of the portfolio items, is also required. The school constructs an evaluative frame for development by using portfolio exhibitions and by involving staff from all school divisions in the development of standards and evaluation of the portfolios. Three figures illustrate aspects of the portfolio process, and an appendix gives a sample science portfolio. (Contains 16 references.) (SLD)