This is a very difficult question to answer. Yes, there are national certifications by the American Farriers Association. There are many farrier schools -- some very good and some not so good. Graduating from a farrier school does not necessarily make one a good farrier, just as being certified does not necessarily make one a good farrier. Just as mechanics, doctors, plumbers, electricians, etc., must be certified and/or licensed does not make them good; it simply means at some time they passed a test. They were good enough to pass the test, but that isn't necessarily indicative of the work they might perform now. It is, however, one criterion to use. We suggest that you look for someone who is knowledgeable in the discipline that you ride to start. We also suggest you check references. Having someone who shows up when scheduled and who returns calls is very important. Generally someone who is reasonably close to you will be of benefit. Having a farrier who attends clinics, belongs to associations and generally tries to stay abreast of new developments in the farrier field is desirable.