There are three ways to become a DEMHIST member:
1) You are not an ICOM member
ICOM has two types of committees: National Committees (by country) and International Committees (by speciality). You enter ICOM through your National Committee (e.g. ICOM Portugal, ICOM US) and then choose your main International Committee, which would be DEMHIST.
Download the membership application form here (or directly from your National Committee).
Fill out the form and indicate that you wish to be a DEMHIST voting member. Send it to your National Committee for approval. See their contacts at http://icom.museum/en/network/committees-directory/
2) You are an ICOM member but your main International Committee is not DEMHIST
Download the membership application form here. Fill it out and send it to email@example.com. Do not forget to copy the DEMHIST Secretary firstname.lastname@example.org
3) You are a member of other International Committees but want to move to DEMHIST
Send the following message to the ICOM Membership service via email@example.com:
”I am a ICOM member and wish to become a voting member of DEMHIST. Please register me with DEMHIST / change my voting choice to DEMHIST.”
Strike out as appropriate, and add your name and ICOM number. Do not forget to copy the DEMHIST Secretary - firstname.lastname@example.org