Understanding and implementing effective classroom assessments are skills that are essential to increasing student achievement. Unfortunately, many teachers have had little training in assessment strategies in either graduate or undergraduate programs. Administrators, therefore, must find innovative ways to help their teachers think like assessors so that they can design their assessments on the basis of what they want students to know before they plan their instruction (Wiggins & McTighe, 1998). Thinking like assessors requires educators to think about how to reach each student, talk about assessments for learning, and implement new processes for improving teaching and learning. Shifting teaching practices is a daunting challenge. These shifts can happen, however, through carefully planned professional development that includes ongoing assessment of the progress staff members are making, continually offering options that are geared to staff members' readiness, and consistently voicing the vision of assessment for learning. (Contains 3 figures.)