[1] He received his Ph.D. in Mathematics from Harvard University in 1984, under the supervision of Barry Mazur.
In 1993–94 he spent a year at the Institut des Hautes Études Scientifiques, and in 1995–96 he spent a year at the Institute for Advanced Study on a Centennial Fellowship from the American Mathematical Society.
In 2006 he founded the Institute for Mathematics & Education at the University of Arizona.
In 2009–2010 he was one of the lead writers for the Common Core State Standards in Mathematics.
His professional interests include arithmetical algebraic geometry and mathematics education.