AMS #1119, WE sectional: University of Utah, Salt Lake City, UT; April 9-10, 2016. (AMS Special session on Extremal Problems in Graph Theory with M. Picollelli.)
AMS/MAA Annual meeting: San Diego, CA; January 9, 2013. (AMS Special session on Graph Theory with M.J. Pelsmajer and D.B. West.)
AMS/MAA Annual meeting: San Francisco, CA; January 15, 2010. (SIAM minisymposium on Graph Theory with H.A. Kierstead.)
AMS/MAA Annual meeting: San Diego, CA; January 9, 2008. (SIAM minisymposium on Graph Coloring and Partitioning with R. Ramamurthi.)
AMS/MAA Annual meeting: San Diego, CA; January 7-8, 2008. (AMS Special session on Graph Theory with K.B. Reid.)
SIAM conference on Discrete Mathematics: Nashville, TN; June 13-16, 2004. (Minisymposium on Extremal Combinatorics with D. Mubayi.)
NSF/CBMS conference in the Mathematical sciences: CSU San Marcos, San Marcos, CA; June 7-12, 2004. (Coorganizing with R. Ramamurthi.)
SIAM conference on Discrete Mathematics: San Diego, CA; August 11-14, 2002. (Minisymposium on Communication Networks with R. Ramamurthi.)
SIAM conference on Discrete Mathematics: San Diego, CA; August 11-14, 2002. (Minisymposium on Graph Classes.)
AMS/MAA Annual meeting: San Diego, CA; January 6-8, 2002. (Special session on Graph Theory with K.B. Reid.)
Minisymposium on Extremal Graph Theory: The Fields Institute, Toronto, ON; March 13-16, 2000.

Combinatorics Seminar: University of California San Diego, La Jolla, CA; February 13, 2018.
Combinatorics Seminar: Renyi Mathematical Institute of the Hungarian Academy of Sciences, Budapest, Hungary; February 16, 2017.
Graph Theory Seminar: Technical University of Denmark, Lyngby, Denmark; January 11, 2017.
Graph Theory Seminar: Technical University of Denmark, Lyngby, Denmark; November 14, 2016.
AMS #1108, WE sectional: University of Nevada Las Vegas, Las Vegas, NV; April 18-19, 2015.
Summit 240: Frankl+Füredi+Györi+Pach: Budapest, Hungary, July 7-11, 2014.
Mathematics Seminar: Karlsruhe Institute of Technology, Karlsruhe, Germany; July 4, 2014.
Westfest: Institute for Mathematics and its Applications, Minneapolis, June 20-21, 2014.
AMS/MAA Annual meeting: Baltimore, MD; January 15-16, 2014. (AMS Special session on Structural and Extremal Graph Theory.)
Mathematics Seminar: Karlsruhe Institute of Technology, Karlsruhe, Germany; July 18, 2013.
Applied Mathematics and Computer Science seminar: Technical University of Denmark, Lyngby, Denmark; June 25, 2013.
SIAM conference on Discrete Mathematics: Dalhousie University, Halifax, NS; June 18-21, 2012.
IPAM long program on Combinatorics, 2 year reunion conference : UCLA conference center, Lake Arrowhead, CA; June 10-15, 2012.
AMS/MAA Annual meeting: New Orleans, LA; January 6-9, 2011.
AMS #1058, CE sectional: St. Paul, MN; April 10-11, 2010.
AMS #1047, CE sectional: Champaign-Urbana, IL; March 27-29, 2009.
ACCOTA 2008: Oaxaca, Mexico; December 9-13, 2008.
Mathematics Colloquium: San Diego State University, San Diego, CA; October 12, 2007.
AMS #1030, CE sectional: Chicago, IL; October 5-6, 2007. (Another link)
AMS #1027, WE sectional: Tucson, AZ; April 21-22, 2007.
AMS #1025, CE sectional: Oxford, OH; March 16-17, 2007.
Joan Hutchinson's 60: Denver, CO; May 17-20, 2005.
Dept of Computer Science Seminar, Indian Institute of Technology, Bombay, India; January 8-9, 2004.
AMS #989, CE+WE sectional: University of Colorado, Boulder, CO; October 2-4, 2003.
Workshop on Extremal Graph Theory: Budapest and Lake Balaton; June 16-27, 2003.
Microsoft Research Theory Group: Redmond, WA; April 17-22, 2003.
AMS #985, CE sectional: Bloomington, IN; April 4-6, 2003. (Another link)
SIAM conference on Discrete Mathematics: San Diego, CA; August 11-14, 2002. (Talk in Minisymposium on Generalized Ramsey problems.)
Discrete Mathematics and Algorithms Seminar, Arizona State University, Tempe, AZ; April 26, 2002.
AMS #965, WE sectional: University of Nevada Las Vegas, Las Vegas, NV; April 21-22, 2001.
AMS #963, SE sectional: University of South Carolina, Columbia, SC; March 16-18, 2001.
Georgia Technological Institute Discrete Mathematics seminar: March 15, 2001.
Iowa State University Seminar: November 7-11, 2000.
CoNE meeting: Smith College, Northampton, MA; April 15, 2000.
Discrete Mathematics Colloquium: Illinois State University, Normal, IL; April 5, 2000.
Graduiertenkolleg Seminar: Universität Trier, Germany; June 21, 1999.
Kombinatorik Seminar: Universität Bielefeld, Germany; June 16, 1999.
Kombinatorik Seminar: Universität Hamburg, Germany; June 15, 1999.
12th Cumberland Conference: Louisville, KY; May 20-22, 1999.
Discrete Mathematics Colloquium: Illinois State University, Normal, IL; April 28, 1999.
Kolloquium: Freie Universität Berlin, May 18, 1998.
Angewandtes Kolloquium: Universität Bielefeld, April 29, 1998.
MTA Sztaki Seminar: Budapest, April 6, 1998.
AMS #931, SE sectional: University of Louisville, Louisville, KY; March 20-21, 1998.
Oberseminar Diskrete Mathematik: Universität Trier, January 10, 1997.

Hypercube 2002, University of Puerto Rico, San Juan, PR; March 21-23, 2002.
Combinatorics Seminar, University of California San Diego, La Jolla, CA; February 26, 2002.
MIGHTY XXXIII: Wright State University, Dayton, OH; October 13-14, 2000.
10th SIAM conference on Discrete Mathematics: Minneapolis, MN; June 12- 15, 2000.
9th Quadrennial International Conference on Graph Theory, Combinatorics, Algorithms and Applications: Western Michigan University, Kalamazoo, MI; June 4-9, 2000.
Minisymposium on Geometric representations of Graphs: The Fields Institute, Toronto, ON; April 11-12, 2000.
Graph minors and topological graph theory: The Fields Institute, Toronto, ON; January 17-22, 2000.
13th MCCCC: Illinois State University, Normal, IL; October 14-16, 1999.
DREI '99: DIMACS, New Brunswick, NJ; (week 3) August 2-6, 1999.
Discrete Optimization '99: Rutgers University, Piscataway, NJ; July 25-30, 1999.
AMS / MAA Annual meeting: San Antonio, TX; January 13-16, 1999.
MIGHTY XXX: Ball State University, Muncie, IN; October 24, 1998.
ICM 98: Technische Universität, Berlin, Germany; August 18-27, 1998.
5th Czech-Slovak Int. Symp. on Combinatorics, Graph Theory, Algorithms and Applications: DIMATIA, Prague, Czech Republic; July 6-11, 1998.
12th MCCCC: Indiana State University, Terre Haute, IN; October 30-31, 1997.
Louisville Workshop on Discrete Mathematics: University of Louisville, Louisville, KY; June 2-6, 1997.
MIGHTY XXVII: University of Wisconsin, Oshkosh, WI; May 9-10, 1997.

Networked Life (Celebrating Fan Chung and Ron Graham): University of California San Diego, La Jolla, CA; January 30-31, 2016.
Extremal Combinatorics at Illinois: University of Illinois, Urbana-Champaign, IL; March 16-18, 2013.
AMS #1080, EA sectional: George Washington University, Washington, DC; March 17-18, 2012.
AMS #1063, WE sectional: UCLA, Los Angeles, CA; October 9-10, 2010.
IPAM long program on Combinatorics: Methods and Applications in Mathematics and Computer Science : UCLA, Los Angeles, CA; November 23-24, 2009.
SIAM conference on Discrete Mathematics: Victoria, BC; June 25-28, 2006.
Southern California MAA Spring 2004 meet, University of San Diego, San Diego, CA; March 6, 2004.
17th Annual CSU Student Research Competition, CSU Stanislaus, Turlock, CA; May 2-3, 2003.
Southern California MAA Spring 2003 meet, Harvey Mudd College, Claremont, CA; March 8, 2003.
Southern California MAA Fall 2002 meet, Cerritos College, Norwalk, CA; October 12, 2002.
IPAM workshop on Phase transition and Algorithmic Complexity, Los Angeles, CA; June 3-5, 2002.
Southern California MAA Spring 2002 meet, California Institute of Technology, Pasadena, CA; March 16, 2002.
AMS #957, CE sectional: University of Toronto, Toronto, ON; September 23-24, 2000.
Workshop on Flows, Cycles, and Orientations : Simon Fraser University, Burnaby, BC; July 3- 14, 2000.
Structured Families of Graphs: The Fields Institute, Toronto, ON; May 8-13, 2000.
Workshop in Honour of Stephen A. Cook: The Fields Institute, Toronto, ON; April 28 - 29, 2000.
Minisymposium on Triple systems: The Fields Institute, Toronto, ON; February 28-March 3, 2000.
Probabilistic Graph Theory: The Fields Institute, Toronto, ON; February 14-19, 2000.
Polyhedral and semidefinite programming methods: The Fields Institute, Toronto, ON; November 1-6, 1999.
Approximation algorithms for hard problems in combinatorial optimization: The Fields Institute, Toronto, ON; September 26- October 1, 1999.
NSF/CBMS Regional Conference in the Mathematical Sciences: Lexington, KY; May 24-28, 1999.
AMS #941, CE sectional: University of Illinois, Urbana, IL; March 18-21, 1999.
36th AACCCC: University of Illinois, Allerton House, Monticello, IL; September 24, 1998.
35th AACCCC: University of Illinois, Allerton House, Monticello, IL; September 29, 1997.
Combinatorial Year: MSRI, Berkeley,CA; May 14-19, 1997.
AMS #919, SE sectional: University of Memphis, Memphis, TN; March 21-22, 1997.
8th Quadrennial International Conference on Graph Theory, Combinatorics, Algorithms, and Applications: Western Michigan University, Kalamazoo, MI; June 3-7, 1996.
Catlin Memorial Workshop: Western Michigan University, Kalamazoo, MI; June 1-2, 1996.
MIGHTY XXV: Illinois State University, Normal,IL; September 30, 1995.
8th Cumberland Conference: Nashville, TN; April 14-16, 1995.
MIGHTY XXIII: Western Michigan University, Kalamazoo, MI; October 8, 1994.
ICM 94: ETH & UZ, Zürich, Switzerland; August 3-11, 1994.
AMS #882: Northern Illinois University, DeKalb, IL; May 20-23, 1993.

Explanation of abbreviations:

AACCCC - Annual Allerton Conference on Communication, Control, and Computing

AMS - American Mathematical Society meeting

CoNE - Combinatorists of New England

DIMACS - Center for Discrete Mathematics and theoretical Computer Science

DREI - DIMACS Research and Education Institute

ICM - International Congress of Mathematicians

IPAM - Institute for Pure and Applied Mathematics

MAA - The Mathematical Association of America

MCCCC - Midwestern Conference on Combinatorics, Cryptography and Computing

MIGHTY - MIdwest GrapH TheorY meeting

MSRI - Mathematical Sciences Research Institute

SIAM - Society for Industrial and Applied Mathematics conference