Given the importance of applied learning and skills needed in sustainability education, this study sought to explore how electronic portfolios enable students to provide a range of evidence to demonstrate their sustainability learning. Michigan State University developed an undergraduate minor on sustainability that required students to provide portfolio evidence of learning in eight required competency areas. Analysis of portfolio contents during 2011-2013 demonstrates that students most frequently addressed Ecological Integrity and Civic Engagement competencies and least often submitted evidence that addresses Personal Awareness and Aesthetic Understanding. In terms of sources of evidence, students most often submitted evidence from their required sustainability capstone and practicum courses, followed by elective academic courses and the required introductory course. Students least often provided evidence from non-curricular experiences. A major drawback to the approach was a student tendency to wait until the final semester to work on the portfolio. Given the change in pedagogy and approach from the standard institutional practice, students would have benefitted from a more structured and formal portfolio orientation program.