Following is a list of links to different professional organization websites. This list is not exhaustive but is meant to give you an idea about the different types of organizations library professionals can be involved with during their career.
Many organizations have student membership rates, so be sure to check for that if you're interested in joining. It is never too early to start thinking about attending a conference or working on a committee, so be sure to check that out as well!
General Library Associations:
Academic Libraries
Art Libraries
Law Libraries
Map Libraries
Medical Libraries
Music Libraries
Special Libraries
Theological Libraries