Researchers and educators acknowledge that early reading instruction is of critical importance, with interventions and remedial programming most effective in the primary grades. Integral to this programming are educators' abilities to assess students' reading strengths and needs, with inconsistent and/or inaccurate practices ultimately threatening students' learning potential. This two-year project explored the effects of teachers' participation in an action research professional learning community, focused on the development and use of primary-grade cumulative literacy assessment portfolios, in an attempt to streamline assessment practices and facilitate implementation of responsive early reading programming. (Contains 1 table and 3 figures.)