These organizations exist to support, educate and provide resources for professionals in a particular industry or profession. Some are really small and others are as huge as corporations. Some are full of young members and others could use some fresh faces. Some are super active and some only meet occasionally. This means you have to do your research (check out the American Society of Association Executives, the professional association for associations) and ask your professors which associations they think are worthwhile. Note that professional association memberships can be expensive, so always ask for student or young professional rates when you join.
What can a professional association do for you? Here are some suggestions:
Image: ABC News Photo Illustration/AP Photo