There are many reasons to consider membership in a professional networking group. The specific benefits that members get directly are covered in the file "Advantages". Some of the less obvious benefits are covered here.
The first is the fact that they are *professional*. These organizations have standards and procedures that help to ensure the success of their members. The level of standards maintained by a solid networking group is a protection not only for the customers you might recommend to the other members, but to your own reputation as well.
The biggest factor in this is the ability of an openly enforced system to keep things balanced and businesslike. If there are disagreements, they can be handled by an impartial outside mediator that has the well being of the entire group in mind. This presence actually helps to prevent such uncomfortable possibilities from becoming reality.
Professional organizations also provide a template for helping to smooth the process of formation of local chapters. They provide the proper legal and marketing experience to get things moving in the right direction without a lot of wasted time and money.
A good organisation will also provide direction and programs for marketing the new chapters to businesses in your area. This alone will make a huge difference in the success of your local efforts.
Add the training in networking skills provided by the umbrella organization and the ability to transfer from one chapter to another in case of a relocation of your business, and you can see that professional groups have a lot to offer.
For a summary of the more immediate benefits, see the section on Advantages.
ProfNet is a professional networking group with over 30 chapters throughout the US and expanding to international markets.