Conceptually, learning progressions hold promise for improving assessment and instruction by precisely outlining what students know and don't know at particular stages of knowledge and skill development. Based upon a synthesis of the literature, a rationale for the use of learning progressions maps to clarify how learning progresses in English language arts and mathematics is provided. How these maps can characterize learning for students, including those with significant disabilities and intellectual gifts, is discussed. In addition, large-scale learning progressions projects undertaken in Australia, New Zealand, and the United States are described. We conclude the paper with a discussion about specific ways in which the application of learning progression maps can enhance current assessment and instruction practices for supporting the learning of "all" students.