- Member, Advisory Board, American Institute of Mathematics, 1997-present.
- Editorial Board, Electronic Research Announcements, American Mathematical Society, 1995-97.
- Chair, Local Arrangements Committee, Seattle MathFest (annual joint meeting of the American Mathematical Society and the Mathematical Association of America), August, 1996.
- Co-organizer, Symposium on the Riemann Hypothesis, University of Washington, Seattle, August 12–15, 1996.
- Co-organizer, Conference on Number Theory and Dynamics, C.I.R.M, Luminy, France, July 4-8, 1995.
- Member, American Mathematical Society Task Force on Excellence, 1995-2000.
- Member, Mathematics Education Reform Task Force, 1993-1999.
- Organizing Committee, Workshop on Computer Visualization of Geometric Objects, Mathematical Sciences Research Institute, Fall, 1992.
- Organizing Committee, Program in Symbolic Dynamics, Mathematical Sciences Research Institute, September–December, 1992.
- American Mathematical Society Centennial Fellowship Committee, 1991-93.
- Organizing Committee, Conference on Arithmetics and Symbolic Dynamics, CIRM, Luminy, France, September, 1991.
- Vice Chairman of Board of Trustees, Mathematical Sciences Research Institute, Berkeley, 1991–95.
- Chairman of the Computing Advisory Panel, Mathematical Sciences Research Institute, Berkeley, 1989-95.
- Co-organizer, NSF-CBMS Conference on Algebraic Ideas in Ergodic Theory, University of Washington, July 17-21, 1989.
- Co-organizer, Workshop on Ergodic Theory and Symbolic Dynamics, University of Washington, June 19-July 16, 1989.