The majority of OECD countries now implement one form or another of standards-based assessment and evaluation. The core logic of standards-based systems rests upon the alignment of three key elements: standards defining the knowledge and skills – or competences – students are expected to have attained at different stages of their education; curricula, which cover the objectives identified in standards; and student assessments and school evaluations which measure attainment of standards. If systems are misaligned, it is impossible to draw valid conclusions about the success of student learning or to develop effective strategies for school improvement. Yet, no system can achieve perfect alignment. This report proposes that rather than thinking of alignment literally, as a lining up of the various elements and actors across systems, it may be more appropriate to approach it as a matter of balance and coherence. The discussion touches on both the technical and social dimensions of alignment.