There are a number of other microscopy, imaging and flow societies around the world, and the following are just some of them. (RMS Members automatically have membership of the EMS).
Australian Microscopy & Microanalysis Society
BioImaging North America
Cryo Microscopy Group
European Light Microscopy Initiative (elmi)
European Microscopy Society (EMS)
Institute of Physics, Electron Microscopy and Analysis Group (EMAG)
International Federation of Societies for Microscopy (IFSM)
International Society for Advancement of Cytometry (ISAC)
The Israel Society for Microscopy (ISM)
Microscopical Society of Canada (MSC-SMC)
Microscopy Society of America (MSA)
Microscopy Society of Ireland (MSI)
Microscopy Society (Singapore)
Quekett Microscopical Club
Scottish Microscopy Society (SMS)
The Society of Electron Microscope Technology (SEMT)