Personalized learning (PL) is spotlighted as a way to transform K-12 educational systems. PL customizes learning pace, instructional methods, and learning content to individual students. As much as PL sounds promising and complex, little guidance is available to educators and policymakers about how to effectively design PL. Five essential features are identified through a literature review: (1) personalized learning plan, (2) project-or problem-based learning, (3) competency-based student progress, (4) criterion-referenced assessment for ensuring student learning, and (5) multi-year mentoring of students by a teacher. This article discusses the educational benefits and design principles of each feature.