This article describes using Work Action Analysis (WAA) as a method for identifying requirements for a web-based portal that supports a professional development program. WAA is a cognitive systems engineering method for modeling multi-agent systems to support design and evaluation. A WAA model of the professional development program of the Information Technology in Science Center for Teaching and Learning is presented. This model is used to identify many system elements that are acted on by the different roles in the system and should be supported by a portal. While the current portal used by the center supports some of these functions, to support all of them, it must be modified or replaced. This technique for developing web portal requirements can be used by other professional development programs. (Contains 4 figures and 1 table.)