In order for you to register a quarter horse, you need both of it's parents names and registration numbers. Any chance of finding those? You will also need to become a member of AQHA. One year membership is $30, 3 years is $65. We are lifetime members which costs $400 now and we register all of our babies before 7 months of age, which costs $25 per foal for members. I'm looking at our reg. Applications, and if your horse is over 2 years old, it costs $1000 for non-members and $1030 for non-members. It's up to you, but personally, I'd save my money. If you do find his parents names, I'd be happy to research them for you. I have access to AQHA's database of registered horses and do quite a bit of research that way.