If you don't have small hands or a specific need for a small bag I would definitely recommend the large size. It's a simple design for a simple task which is all I'm looking for. It's waist-cord is a bit of a hassle, though. It must be tied each time it is put on and the cord material lends itself to loosening so make sure to tie a good knot. Nothing that can't be fixed by a separate belt for a few dollars more.

I must agree with the others. I bought this bag for my 7 year old daughter who is on a rock climbing team. It holds the chalk in great (we have a chalk ball), but I will have to rig something up for connecting the bag to her belt. It is very hard to get on and off with the string. You must tie and untie a knot every time.

It has the right and exact size for the amount of chalk I use. Simply perfect...

I've used a lot of chalk bags in my days, but this one is the perfect size for the amount of chalk I use on a day at the crag or gym...the brush holder's great too! Could use a pocket, but at this price it's really hard to complain.

the Diamond back chalk bag is the best I ever used and all you will need.

This bag is decent in terms of holding a good deal of chalk, however, unlike all the other bags that I have seen, this one comes with a big loose string instead of a belt or belt-like rope to hold it to you. I haven't really figured out how to keep it on me when I'm climbing yet. Other than that, It does what it supposed to do, and It can hold a whole lotta chalk.

I like the size of this chalk bag - just big enough. I also appreciate that once it is cinched down, chalk will not escape.

I purchased a Medium BD chalk bag for indoor climbing and it fits the bill very well. The quality is excellent. I'd say anyone who purchased this bag will be happy. If I bought another one I'd buy it in a funky pattern this time :-)
I'm also very happy with the customer service from BackcountryStore.com

The bag works great, it holds chalk and keeps it from going everywhere; however, the cord to hold it on has to be tied every time you use it. Slightly inconvenient.

Just your standard chalk bag: it has multiple anchor points, and it gets the job done.