ICIAM has no individual members, but is a society of member societies. Member Societies are in one of two categories, each with sub-categories according to the number of its members:

- Full members are those which are dedicated primarily to applied and/or industrial mathematics;
- Small societies have 10-99 members and pay dues of USD 200 per annum (for 2023)
- Medium societies have 100-999 members and pay dues of USD 400 per annum (for 2023)
- Large societies have at least 1,000 members and pay dues of USD 800 per annum (for 2023)

- Associated members may also have other interests but still significant activity in applied and/or industrial mathematics.
- Small societies have 50-999 members (of which at least 10 are applied mathematicians) and pay dues of USD 200 per annum (for 2023)
- Large societies have more than 1,000 members (of which at least 500 are applied mathematicians) and pay dues of USD 400 per annum (for 2023)

Any society wishing to join ICIAM should contact the ICIAM President stating their number of individual members and the number of those working predominatly in Industrial and Applied Mathematics.