I baked a batch of dark chocolate rolled sugar cookies (recipe is on this site) yesterday but they were really soft, almost brownie soft. I was afraid of picking them up in case they split apart. In fact, even with the royal icing on and hardened, I'm still afraid they might crack when I pick them up.

Can I get thoughts on how to make the cookies crunchier and firmer?

I wrote this down from somewhere, maybe America's Test Kitchten....for chewey cookies add melted butter. For thin, candy-like cookies add more sugar. For cakey cookies add more eggs. For open, coarse crumb and craggy top add baking soda. For fine, tight crumb and smooth top add baking powder. Maybe this will help.

How thick are you rolling them out?

I keep mine about 1/4 in thick and they(especially the dark chocolate ones) stay fairly crunchy even when iced.

I watched an Alton Brown episode on this very thing! Crunchier and firmer are two different things, so I'll start with crunchier. White sugar helps cookies become crunchier. As would rolling thinner and baking a little longer. For firmer (I assume you mean so they don't fall apart?) I have read from one of his books that eggs are what gives the cookie structure, so maybe add an extra egg?

Here is a link to that episode that I saw and there are 3 different cookie recipes (thin, chewy, puffy) for chocolate chip cookies, but I would think that each ingredient does the same basic job no matter what the dough, so I'm sure you could look at your sugar cookie recipe and tweak it in the same ways. http://www.foodnetwork.com/good-eats/three-chips-for-sister-marsha/index.html