I took a look at a list of All-Clad roasters, and only one mentions tri-ply. Of course, it's the most expensive one: the stainless steel oval roaster. But I think most of the others do mention an aluminum core, so I'm sure you'll be fine.

Here is a link that might be useful: All-Clad roasting pans

The All-Clad roasting pans in the stainless line are pure stainless steel. They have no aluminum core. There have been reports also of warping as there is no core. This happens mostly when using higher heat. It's a good pan though.
If you want the core look at the Calphalon stainless roasting pan in the Contemporary line (also Cooks Illustrated pick), or the Kitchenaid roaster in their 5-ply stainless line.

Mauviel makes a heavy aluminum roasting pan, available with or without a non-stick lining. We're very happy with ours.

blondelle, the All-Clad roasting pans all have an aluminum core, and the SS oval roaster specifically mentions that it is tri-ply. Check out any site that carries them.

From an article on roasting pans in the Los Angeles Times:

"Of the three stainless pans we tested, the expensive All-Clad, with its solid core of aluminum, performed best."

I'm not necessarily advocating All-Clad roasting pans, but they do have an aluminum core.

Here is a link that might be useful: Roasting Pans (Los Angeles Times)

Did your All-Clad roaster come with a little instruction pamphlet? I would think that, if there is one, it would describe the construction of the pan and whether it is clad or solid.

After reading the cooks illustrated article and looking at the pan in detail, I returned it as I'm convinced it isn't clad. I think a lot of people assume it is clad because of the name (a lot of internet stores list it as clad). Bought a calphalon one instead which is great.

It's also listed as having a core on several sites, but that's an error. I have the box in front of me and it's solid stainless. A call to All-Clad also confirmed it has no core I made a while ago. That's why there were problems with warping. It's solid stainless I'm afraid! Lots of misinformation out there!

It's a terrible roasting pan. Last night's goose was good, but, when I took it out of the oven, the pan looked like it was covered in varnish. After soaking, using Barkeeper's Friend, and using Dawn Power Dissolver, the bottom of the pan still has brown spots, as do the rivets and handles. Stainless steel is not a good conductor of heat, and I used the directions on the goose's label: 375 for 2 hours 20 minutes. If a pan cannot roast at 375, why is it marketed as a roasting pan? The pan came with the oven and it's the only one I have large enough for that goose, but it's a real pain. It's going to be a three-day cleaning job.

"Stainless steel is not a good conductor of heat"

Kitchendetective, the problem you describe doesn't sound as if it's related to heat conductivity problems, which really applies more to stovetop cooking. If you think about it, the importance of an aluminum core in a roasting pan is more for strength, so that the pan doesn't warp, as blondelle pointed out. Of course, if you want to use the pan on your stovetop to deglaze or whatever, then, yes, you might not have the best heating situation and you might get warped.

Although I wouldn't trust a thin SS roasting pan, I have a high-quality one that I've used for more years than I care to say without any warping or cleaning problems.

Right, suzyQ, but one of the explanations for the staining is that one should cook on lower heat--which you can't actually do and still get the desired result. The pan came with my Dacor 36", perhaps because the company was trying to emphasize the size of the oven, but I am planning to find a better extra-large roaster. Also, others have indeed complained about warping with the AC ss roaster, although I haven't encountered that.

Misinformation indeed. All-Clad products (the ones that DO have an aluminum core) are MORE subject to warping because of that core and the expansion rates of the different metals. Hence the recommendation for low to moderate heat only.

I got the small roaster (yes, clearly labeled as just stainless) for Christmas but think I'm going to exchange it. A $160 store credit could buy me much more useful stuff and leave enough left to buy a reasonably priced one.

Aluminum adds conductivity, stainless adds strength and protects from reactivity. Whether a pan actually warps also depends on the relative thicknesses of the metals. Thin stainless will warp more than thick stainless. Effectively clad stainless/aluminum combinations should not warp when used as directed, if the metallurgy and engineering are done properly. All-Clad's claim to fame is its metallurgy. I've never had a problem with warping when using AC stovetop products, although I do not care for the handle design, which is the main reason I no longer use them. I do believe the SS roaster, however, is a vastly overpriced product that does not perform as promised. Had I bought it, I would return it, too.