You could add wood pieces to either side of the shelf wall and then slide it over them to hold in place.

Or you could use some sort of bracket. Maybe they have clear ones so they do not show up.

The first idea would look more "built in" Also you could add a bracket in the back with the two wood pieces for additional security and you would see it less.

As mentioned above, I'd nail up a 1"x2" cleat on three sides and set the shelf on top. On the wall on the right, I'd nail into a stud or use a drywall fastener.

Looked at your pic again. I'd nail into a stud or use a drywall fastener across the back wall too.

We will try that! Thank you!

I'm going to post two pictures of my linen closet shelves - the first shows how they were "finished by adding a trim piece to the front and the second shows how they were installed. Hope this helps.

Second pic

What did you use for the actual shelving sjhockeyfan? I have a piece of 1/2" furniture grade plywood I was going to use. Wondering if I should use something thicker?

Casey, yes, I think it is furniture grade plywood. It's not thick, hence the trim piece in the front to make it look more finished/substantial.

I've done some measuring and I think if I put 1 x 2's along the 3 sides, get a 1 x 10 and cut it to size, then put another 1 x 2 across the front like trim, it will be the perfect size. I am not good with a saw, circular, jig, hand...so the less I have to cut, the better off I will be. lol I can not wait until I can get to the orange store! :)

One trick for a lightweight shelf with no visible fasteners, cleats, pins, or brackets is to drill four far spaced holes like you would do for four thin shelf pins. Then insert four shelf pins in the form of two lengths of coathanger wire, one on each side, to make a wire spline. Then cut two grooves on the side edges of the snug fitting shelf, nearly to the front, and slide the shelf onto the wire supports. Everything is hidden.

You use the wire instead of four discrete pins to spread the contact area in the groove, which is weaker than an ungrooved shelf. Advantage: very neat. Disadvantage: you need some skills to make a good clean slot.

I DID IT! I think it is strong enough to hold the stuff we will be putting on it! It's not perfect, but I did it myself!! :) And it's level! LOL I will paint it Chantilly Lace like the cabs!

Nicely done!