Lifelong learning has emerged as an important learning outcome across the Canadian post-secondary education system. However, assessments of lifelong learning have been limited to students' self-reports, particularly questionnaires. In programs that offer work-integrated learning experiences, students' reflections may provide a window to further developing this outcome. The purpose of this study was to develop a rubric for assessing lifelong learning in this context. A review of the literature was used to develop both a rubric and self-assessment instrument for measuring lifelong learning. Students in an accounting and financial management co-op program at the University of Waterloo (n = 32) completed the self-assessment and the rubric was applied to two reflection assignments. Staff feedback and correlational analyses provide initial support for the rubric as a useful tool for assessing lifelong learning. Implications for educators especially in work-integrated learning contexts are addressed.