Although being a fellow of the ICA is not itself a highly selective honor, the ICA also maintains another class of members, "honorary fellows", people who have made "pre-eminent contributions to combinatorics or its applications". The number of living honorary fellows is limited to ten at any time. The deceased honorary fellows include H. S. M. Coxeter, Paul Erdős, Haim Hanani, Bernhard Neumann, D. H. Lehmer, Leonard Carlitz, Robert Frucht, E. M. Wright, and Horst Sachs.