You haven't specified a discipline, so I'll answer your question in terms of my own judging focus, the hunters and jumpers. If you're interested in judging dressage, contact the US Dressage Federation at 859-971-2277 or www.usdf.org), which has its own program to train judges. If judging a particular breed is your aim, check with the breed organization; some of them require judge hopefuls to attend special judging schools.
Once you've decided which discipline (or disciplines) you're most interested in judging, study the United States Equestrian Federation Rule Book (check www.usef.org to order) to familiarize yourself with the relevant rules and judging procedures. Educate yourself further by reading books pertinent to the sport. If you're interested in judging hunters, for example, one excellent resource is Anna Jane White-Mullin's Judging Hunters and Hunter Seat Equitation: A Comprehensive Guide for Exhibitors and Judges.
If you can, attend a judges' clinic. The AHSA holds several national clinics on judging hunters, hunter-seat equitation, jumpers, and hunter breeding each year. Although priority is given to licensed and Learner judges, the clinics are usually open to auditors as well.
You may need to travel beyond your local area to find judging jobs because the managers of shows where you normally compete or coach students would rather have you filling one or both of those capacities (which bring in more money) than judging. Also, riders you've competed alongside in the past may not be comfortable with you judging them. If you have to, offer to judge for free at the first few shows. The experience you gain will be well worth the sacrifice.
Taking the steps to earn AHSA judging credentials can be a challenge. It represents a big commitment in terms of time, money, and travel. And because the process is so thorough and the AHSA's standards are so high, it can be quite humbling. A good first step: Get to know an AHSA-licensed judge; ask her about her experiences completing the process and her take on your chances of doing the same.
If you decide to enter the process, your first step is to apply for a Learner Judge permit. You'll need to pay a $60 application fee and submit a detailed resume describing your horse-related experience (the more schooling-show judging jobs you can cite, the better), along with a list of references. An AHSA subcommittee will review your application and decide whether you're qualified to enter the program.
As a Learner Judge, you'll have to meet certain requirements before you can apply to become a licensed "r" (recorded) judge: You must attend a judges' clinic and sit in with judges at a prescribed number of AHSA-recognized horse shows outside your region. To sit in at a show, you must first request permission from the show manager and judge. They have the right to say no and some do, but many are willing and accommodating.
For each show, you'll be responsible for a $40 AHSA fee and for all your own travel expenses. The Learner Judge program takes about three years to complete. After that, you can apply to the AHSA Licensed Officials Committee to be considered for an "r" license. This screening process is even more elaborate; it requires another application fee ($125) and, in the case of jumper judges, a written test.
If you are awarded your "r," you must then judge at a certain number of horse shows and attend additional clinics to become eligible to apply for your "R" (registered) license. Even after earning "R" status, you must judge and attend a minimum number of shows and clinics to maintain your judge's card.
Judging's not for everybody. It can be very prestigious and rewarding, but it can also be demanding, both time- and stamina-wise. And, remember, whether you're judging at a schooling show in a dusty field or in the Dixon Oval at Devon, exhibitors regard your placings as a serious assessment of their horses and/or their riding. Whatever level you're judging, you are expected to be a luminary in the sport, worthy of competitors' respect. So your own track record, as a rider and/or trainer, needs to be clear and on a relatively high level.
Success as a judge can be easier if you've already had a long career as a professional, but some excellent judges have come from the amateur ranks. Such judges usually have either shown extensively or otherwise proven themselves to be very knowledgeable. (By the way, working as a judge, even for pay, does not affect a rider's amateur status.
An AHSA "R" judge, course designer, and steward who's also on a grass-roots committee for the National Hunter/Jumper Council, Gay Talmey grew up fox-hunting and showing in the Midwest. A professional since 1965, she now divides her time between teaching, training, and showing at home and officiating around the country from Indio to Alaska. She and her husband, Steve Bischoff, also breed sport horses on their Cottonwood, California, farm, Rancho Alegre.