There is a growing interest in conceptualizing, defining, and assessing what are often called 21st century skills or deeper learning competencies. The purpose of this literature review is to explore the conceptualizations, definitions, and understandings in the research literature related to self-directed learning. Key initial questions include: What is self-directed learning? How is self-directed learning related to other success skill concepts? And how do self-directed learning skills develop over time? This foundational information is then used to examine: (1) instructional approaches to promote self-directed learning; (2) benefits of self-directed on valued student outcomes; and (3) ways teachers can collect evidence that reveals the benefits of student self-directed learning outcomes using student artifacts and other appropriate measures.