For each W3C group there is:

1. A form for joining the group
2. Instructions for joining the group (for both Members and non-Members)

Those resources are linked from any call for participation in the group and the list of groups.

A Member's Advisory Committee Representative joins any group (that is more than a mailing list) on behalf of that Member. If you wish to join a group, please first contact your Advisory Committee Representative.

Here are the general instructions for Advisory Committee Representatives (assuming they have a W3C account; if not please complete the Member Access Request Form):

1. Read the group charter
2. Complete the form for joining that group. Note: Once you have joined a group, the same URI is used to offer a form to leave the group.
3. Nominate one or more individuals to represent your organization in the group; the link to that form is available from the "join" form.