Joe, the sleeping bag did well into the 30's. I, however, did not. (see my next thread)

I am confident that with some layers, this bag would do fine down to freezing temps. I tend to be, I forget how they classify it, a warm sleeper maybe? I like to be really warm. Or at least tired enough to sleep... Again, see other thread.

But the bag did well and performed as expected. I don't think you could climb in it in your undies in 20 degree weather and be perfectly fine, but who does that?

EDIT: I don't feel like I explained the bag well at all. Let me try again.

I was wearing pants, socks, LS wool base layer, LS wool sweater and a wool beanie. This is about normal layering wise for winter sleeping in my opinion. The bag itself into the mid 30's was plenty warm. I had no complaints about the bag. It was even comfortably warm. It could probably do fine down to the 20 degree mark as advertised.