American Dietetic Association: With more than 68,000 members as of this writing, the American Dietetic Association (ADA) is the world’s largest group of dietary professionals. Its members are involved in all aspects of the field of nutrition and health, including research and education. Its booklet Becoming Vegetarian (2007) outlines the fundamentals of a basic vegetarian diet and provides tips on how to eat out vegetarian and ways to shift to a vegetarian way of eating.

International Vegetarian Union (IVU): The acknowledged grandfather of the international vegetarian movement, the IVU came into being in the early 1900s in Germany during the first vegetarian congress. A nonprofit group, its sole purpose is to promote vegetarianism worldwide, a goal they want to achieve by holding regular congresses, answering questions, dispensing diets and recipes, and maintaining an archive on vegetarian-based information.

Moosewood Restaurant: Upstate New York restaurant under the aegis of Moosewood Inc., which is commonly credited with kicking off the boom of vegetarianism in the United States. The restaurant, which opened in Ithaca in the early 1970s, certainly took vegetarian cooking and ideals and made them palatable and interesting to a new generation of Americans. As a collective, the restaurant’s staff wrote and published the original Moosewood Cookbook, which attracted both fame and notoriety to the place.

Oldways Preservation Trust: Founded in the 1980s by Bostonian K. Dun Gifford, the Oldways organization has as its mission simplifying nutritional science and converting food facts into palate-pleasing fare. Gifford and colleague Sara Baer-Sinnott have initiated numerous food-related activities and conferences to promote better health through better diets. Its staff have also developed consumer materials, including several diet pyramids and a cookbook entitled The Oldways Table.

The Vegetarian Society of the United Kingdom: Formed in England in 1847, the society is the longest-running all-vegetarian group in the world, espousing and supporting an all-vegetarian lifestyle that includes many levels of activities, from fund-raising, lecturing, and providing nutritional advice to creating recipes and teaching cooking. The group also established and runs the annual National Vegetarian Week with concurrent activities.

Vegetarian Resource Group (VRG): The VRG is a source of vegetarian information, vegetarian (actually, vegan) recipes, and a resource for all aspects of a vegetarian lifestyle, with even a listing of vegetarian travel services and tips on how to order vegetarian when dining out. In addition to its very complete website, the VRG has archived numerous vegetarian-based articles and has published vegan cookbooks as well as a newsletter and a magazine entitled The Vegetarian Journal.

About.com Vegetarian: About.com's vegetarian resource page, complete with info, recipes and tips for all types of vegetarians.

What Type of Vegetarian Are You?: Figure out your type with this list of the top 7 types of vegetarians.

Boston.com Vegetarian Food: Where to find the best beans in Beantown.