Equestrian air vest look and design has come a long way. These days, there are multiple options for sleek, low profile fits as well as air vest compatible clothing that you can wear over your equestrian air vest to make your vest nearly invisible. 

So, should you wear your air vest over or under your show coat? That depends on multiple factors. Let's explore them.

1. What type of air vest do you have? There are currently only three horse riding air vests on the market that have air vest compatible clothing that can be worn over them - Helite, Horse Pilot, and FreeJump. 
2. Is your coat air vest compatible? Your air vest must always be your outer-most layer unless the coat has been lab tested by one of the air vest manufacturers and deemed to be air vest compatible. This means that the coat will stretch appropriately so as not to impeded the inflation of the air vest as well as to ensure that the garment isn't damaged. Dada Sport, Helite, and Horse Pilot offer air vest compatible clothing.
3. Budget - If you are just getting into an air vest, they are absolutely a worthwhile and important investment. That investment for one of the above mentioned air vests ranges from the mid $700 range to low $900's. An air vest compatible garment is going to start in the low $300's and go up to $750. I usually tell people that if your budget doesn't allow for the purchase of a new coat, is perfectly acceptable to wear your air vest over your show coat and a large number of people do just that, but next time you buy a coat, get one that's air vest compatible.
4. Desired Look - Some people don't want for their air vest to be noticeable, so they choose to wear it under an air vest compatible coat. These is completely personal preference.

The great news is that you are just as safe wearing your horse back riding air vest over your coat or under an air vest compatible garment. And over time, there will be more and more options for air vest clothing. What is available now is beautifully designed and tailored, so you're not compromising fashion for safety. It's completely up to you and your personal preference.