The Assessment Standards for School Mathematics (NCTM 1995) discusses a shift in mathematical content from just mastering isolated concepts and procedures to exploring a rich variety of mathematical topics and problem situations that teach and use concepts and procedures to solve problems. The Standards document also calls for student assessment that is aligned with, and integral to, instruction. Constructing valid assessments has always been difficult, and the new demands make it even more of a challenge. What does such assessment look like, and how does it work?