The "Common Core State Standards for Mathematics" presents challenges and opportunities to contribute to a common understanding of the mathematical proficiencies expected of our students. This paper discusses the movement to establish multi-state assessment consortia in the United States based in the standards movement set in motion by the National Council of Teachers of Mathematics and the increased accountability of student learning through the "No Child Left Behind Act". The consortia intend to assess the full range of student learning expectations to include both standards for mathematical content and mathematical practices through construction of comprehensive systems of assessments that accurately measure student progress toward college and career readiness. The systems are to include interim and summative assessments primarily taken in an online environment that allows for automated or timely scoring.