Learning progressions – descriptions of increasingly sophisticated ways of thinking about or understanding a topic (National Research Council, 2007) – represent a promising framework for bridging the chasm between cognitive science research on how people learn in a given domain and the methods for teaching and assessing science. Because of this potential, they are rapidly gaining popularity in the science education community. However, there are several issues faced by all engaged in this work. In particular, we have identified four aspects of work on learning progressions that are critical for these tools to make the maximum possible impact in science education: (1) defining learning progressions; (2) developing assessments to elicit student responses relative to a learning progression; (3) modeling and interpreting student performance relative to a learning progression; and (4) using learning progressions. This working conference will provide a structured forum to facilitate discussions around the challenges in learning progressions work and to develop syntheses of ideas for use by the field in future work.