Including professional organizations that you belong to on your resume shows potential employers that you are dedicated to your career, have current knowledge on industry information and are affiliated with other professionals in the industry. Your membership in professional organizations also shows employers that you are outgoing and really care about your career, since you are willing to dedicate a portion of your free time to networking with others in your field and learning more about your profession.
Organizations Related to Your Career
Instead of simply listing the names of organizations you are involved with that are associated with your career, also include the date that you became a member, your title within the organization, and the location of the organization.
If you were previously a member of a professional organization related to your career, but are no longer actively involved, do not include it on your resume unless there is a good reason that you ended your affiliation with the organization. The only acceptable reasons would be things such as the disbanding of the organization or if you moved away to another city.
Non-Relevant Professional Organizations
If you are a member of a professional organization that does not relate to your field at all, consider leaving this off your resume. If you cannot relate your membership to a career objective or some type of characteristic that the employer is looking for, it probably is unnecessary. If you feel strongly about including it, put it under a "volunteer" or "personal" section in the resume.
Religious, Political or Ethnic Groups
Groups that are religious, political, or ethnically motivated are typically better left off your resume. Some of these groups may not create a positive impression on the employer, so unless you are absolutely certain that your membership in one of these groups will impress them, do not include it.