In a community of practice, shared repertoires develop as resources to create meaning in the joint pursuit of an enterprise. Repertoires include tools and routines. This article examines use of a tool, the "Literacy Learning Progressions" ("LLP"), in assessing development in writing. Teachers (Max N = 291) responded to a questionnaire regarding their perceptions of its usefulness in creating meaning and new learning. They rated the extent to which they agreed that the LLP exhibited or were useful for a particular dimension. Strongest agreement was for the items regarding the tool allowing learning to be viewed within a bigger picture and helping show links between reading and writing. Lower levels were reported concerning items related to formative assessment. Analysis of items showed four factors accounting for 60% of the variance. Responses to open questions suggested considerable learning in relation to expectations, pedagogical aspects and the links between writing and reading. Action was reportedly taken with respect to setting expectations or targets; in relation to specific aspects of practice like setting learning goals; in terms of using the LLP to build profiles of students but also using LLP to reflect on practice. (Contains 2 tables.)