Should students earn high school diplomas by demonstrating proficiency in essential standards, instead of through “seat time”? The state of Maine recently answered yes when it passed legislation requiring proficiency-based diplomas in all school districts by 2018. In this article, Maine ASCD president Mary Bellavance describes how school districts are making progress toward this goal by implementing personalized, or customized, learning. In her school district, students track their own progress toward learning goals and demonstrate their proficiency through multiple pathways, including teacher-designed and student-designed assessments, portfolios, performances, exhibitions, and projects.