My sister LOOOOOOOOOOOOVES The Little Mermaid! She never outgrew it.
When I saw this fabric at Walmart I didn't see a cute little girl dress- I saw a maternity top (does that make me weird, too?) So, here is the tutorial on how to make a women's halter maternity top from girls' pre-shirred fabric.
1. Buy the fabric! How much? Well, after standing in Walmart wrapping it around myself and looking like a weirdo because I was surrounded by little girls, yet measuring Little Mermaid fabric on
myself, I decided that I would get 34". She is a little broader than I am- probably about 36" and I wanted it to be snug on the chest anyway. You will need something for straps, too- about 1/4 yard, depending on how wide you want them.
2. Sew it in a tube, WRONG SIDES together in a 1/4" seam!

3. Fold the seam to the inside and then sew right sides together with a 3/8" seam allowance. I pinned this in place before sewing to make it easier. TADA!
A French seam! Eat your heart out, 7th grade home-ec teacher!

4. Now to start on those straps. I would have made them thicker, but I was using up some leftovers from an apron that I made for my sister years ago. So, I cut 2 strips 2 1/2" wide by 36". Feel free to cut yours wider.

5. Iron each strip in half and then press the edges in 1/4" towards the wrong side, being careful not to burn your fingertips. Then fold it back in half again. It's a little like bias tape.

6. Sew 1/8" along the edges of both sides, and fold one end in twice and sew down to get a finished end. (Yeah, I know mine isn't that great.)
7. Last step! Attach those straps! To get the placement, I put her shirt on, considered keeping it for myself, decided my girls would me too jealous, and placed pins where my bra straps were. So, about 3" from the center on each side.

Fold the ends up and sew it to the inside below the first row of shirring. I sewed it in a little box to make it sturdier and hold the ends down, too.

(Ignore that extra line of stitching on the side there. Little mess-up.)
So, that is it! Since it is a halter you are done!!! Just tie it up!
Cute side-view! I made her do it. I just like seeing a pregnant belly on someone else for a change!
She says it makes her look bigger than she really is. (I disagree and it is my blog- HA!)
So, I hope I didn't terribly confuse or bore you to death with this little tutorial. I guess if you wanted to, you could make this as a halter style little girls' dress, too. But where is the fun in that? :)
I will be linking up at some places listed up at the top there!