The purpose of this article is to document the current practice of using portfolios as a tool for assessing students' mathematics learning. Literature related to the assessment of mathematics through portfolios is limited to information generated from a few large-scale and a scattered number of Classroom assessment projects. These reports provide weak support for claims that mathematics portfolio assessments enhance student learning and promote effective communication among teachers, students, and parents. There is a need to establish a strong rationale for selecting a portfolio as a means to assess mathematics. This article offers practitioners and researchers an opportunity to explore the validity of claims and identify factors that confound existing research activities.