In their article "Innovations in Setting Performance Standards for K-12 Test-Based Accountability," Kristen Huff and Barbara S. Plake (2010) lay out three preconditions for continued investment in standard-setting methodology and practice, all focused on the sound development and use of achievement level descriptors (ALDs). Among these preconditions is the use of "empirically-based learning progressions" to inform the articulation of ALDs, drawing upon information about ways in which students make progress towards "more sophisticated, deep understanding". Huff and Plake argue that these ALDs (and, by extension, learning progressions) should then drive test design and item development for educational accountability systems. Learning progressions are proposed as a means of ensuring that students "learn age-appropriate versions of core ideas" through their influence on both curriculum and standards. In this commentary, the author explores several challenges that must be considered in order to make progress toward Huff and Plake's (2010) vision of the way in which learning progressions might inform ALDs and, thus, test design for educational accountability systems. In doing so, the author draws upon recent work on learning progressions in science.