Honorary Membership was limited to 10 from 1890-1900, and to 15 from 1901 onwards. Corresponding Membership was a lesser class of Honoris causa membership in the early years. A few honorary members, such as Barnard, were first made corresponding members for a short time before being recommissioned as honorary members.
| Nation(s) |
Start |
End | |
|---|---|---|---|
| Underhill, Dr. Anne | Canada | 1996 | 2002 |
| Crawford, Dr. David L. | USA | 1997 | 2024 |
| Robinson, Mr. Leif J. | USA | 2000 | 2011 |
| Pasachoff, Dr. Jay M. | USA | 2003 | 2022 |
| Shoemaker, Carolyn | USA | 2003 | 2021 |