I will always be hunting from a treestand. I just went and bought a 6-pack of new Muzzies today (tried and true) and I want to sight my bow in to match the broadheads perfectly. My question is this, can I sight them in on the ground and expect them to work once I get airborn or should I actually get elevated to my hunting height to sight them in? How will it affect my ground target practice if I sight it in 20 feet in the air? I'm going to go with 10, 20 and 30 yards by the way.

There wont be any effect for those short distances, the only thing you need to concentrate on would be where your arrow exits at when that high up.

for simplicity, I would sight in from the ground 1st, tuning to get the BH to hit like FP. Then I would most certainly shoot from a tree, preferably in your hunting jacket. At that point you will know where you hit from a tree. If you keep good form and bend at the waist you should hit the same, but there is no way to know for sure. Also shoot at every distance that you may face, from in tight to your max. For me, it seems like the tighter in I get, the more off my pins are.

YUP, tune them at ground level where you've done most of your practice. You don't want to be adjusting thinking it's a broadhead when it might be a form glitz from an elevated stand. GEt them right and then practice from above with field points.

Well I've already got it on the money with field points from the ground. So there won't be any considerable differences from a treestand with 100 grain 3-bladeMuzzy's?

Not if they hit with your field points. You gotta check that first.

Depends if you know how to shoot from an elevated position. At hunting partner of mine went through a tuff season one year from a tree, couldn't get the arrow to go where he though it should. From the ground he was good.

so I got him into the tree and got the target out and watched him shoot from up there. Well he wasn't bending at the waist to get on target, he though he was but he wasn't. He was dropping his bow arm onto the target only. Well he could never drop the bow arm to the same place so his shots were scattered. Once he got back to bending at the waist he got his grouping back. Bending at the waist very important when up a tree.

If you're asking what I think you're asking, then the solution is simple.

Shots taken from the ground will impact the same place as shots taken from a tree, provided that the pin you use is the one set up for only the horizontal portion of the distance to the target (meaning the path you would walk on the ground to retrieve your arrows.)

It's simpler than it may sound. If the target is 20 yards from the base of your tree, then use the 20 yard pin, regardless of whether you are shooting from the ground or from the tree. That's it. Nothing more complicated than that.

Where folks get burned is when they use a rangefinder or make a visual guess from an elevated position in the same tree, and read 25 yards for that same shot. They end up shooting high because their rangefinder, or their visual guess of yardage is seeing the hypotenuse of the right triangle formed between their stand up in the tree and the distance to the target on the ground.

By the way Swiftflight, this effect actuallyis worse at close range, and becomes negligible when you get out far enough, like at 40 yards or so. If youwere to make this error while estimating a shot at 5 yards, you will hit much farther off than if you were to make the same mistake at30 yards. If the deer is right under your tree, you need to put that 10 or 20 yard pin on the ground between you and the deer. It's that far off. Try it.

This is actually shown quite well in a scenein the movieSaving Private Ryan. A solider, who apparently was the designated marksman for his unit since he was the only one who had a scope on his rifle, was shooting enemy soldiers from an elevated position, and when they showed his view through the scope, it demonstrated that as the enemy got closer, he had to aim lower and lower, sometimes even off the soldier's body. It wasn't explained in the movie, but I was impressed than they would show it that way, instead of the usual crosshairs at dead-center for every shot.

In answer to your question of which way to sight in, that's up to you.
The important part is that you understand the differences, and how far you could be off, and which way you'll be off.
I like to set up forshooting on the ground, and then measure off landmarks on the ground, so I don't get caught trying to guess from above. Pick a couple of trees or other landmarks and use them to estimate the range for stuff in between. If pacing stuff off on the ground is impractical or unwanted due to the risk of spreading your scent, just aim a bit lower than you think you need to for closer ranges.

Also, Illini...
You may want to eliminate your 10 yard pin,or make it a 40.
Unless you're shooting a really slow bow, the difference between 10 and 20 yard pins will be almost too close to see. Keeps the sight picture more open , and lets you see more of the deer.

Start by setting a 20 yard pin, and shooting a group with it at a 10 yard target.
It will hit slightly high, but probably no more than an inch or two.