The Portfolio Project was conducted to promote lifelong, self-directed learning in the workplace. The project, which offered courses on basic skills, supervisory communications, and English as a second language, was initiated as a literacy demonstration project by the Casco Bay Partnership (CBP), which brought together government, educators, and several local businesses in Portland, Maine. The project was based on a portfolio process with four goals: authoring one's learning; documenting the evidence of learning and development; fostering reflective learning; and assessing one's own learning. After a review of the literature on portfolios, a portfolio process tailored to the workplace was developed. It was based on the following principles: make goals explicit for students; keep samples of student work; provide students with a folder or a notebook; build on routines already in place; be persistent in engaging students in reflection; conduct end-of-course portfolio presentations; and set new goals. Case studies of the process in use at three worksites (a producer of wood-boring tools, a manufacturing plant, and a food processing plant) confirmed the effectiveness of portfolios as a means of encouraging professional growth and development in the workplace. In the case studies, portfolios proved to be effective tools for both assessment and development. (MN)