Are they able to take part?

This is in the Help documents:

At present, we are a US-only club.

• PBS members must be able to receive mail at an address served by USPS.
• The PaperBackSwap system uses Media Mail postal rates provided by the USPS.
• Media Mail rates are good for:
  • all 50 US states
  • US territories and commonwealths (American Samoa, Guam and the Virgin Islands; Washington, D.C., the Northern Mariana Islands and Puerto Rico),
  • APO/FPO addresses
  • If you live in any of these areas, you can belong to PBS. 

We've had requests for international membership from all around the world.

• Eventually, we hope to expand.
• We have had a LOT of requests from Canada!
  • We have been working on shipping issues regarding the Canadian postal system. Until we work these out, we will not be able to trade across borders with our system.

I'm sure there are a lot of people like me that can only afford to participate here because of the low media mail rates. 
I couldn't afford to send books to Canada or anywhere else.

I've heard rumors of folks near the border getting a PO box in the US to use for PBS.  

Not through this site but I have sent books to Canada using media mail and its maybe a dollar more then what it usually costs on here.But then I don't use PBS postage,tracking or any of that.They have been saying for  years that they are "working on it"should be able to come up with a way to do it.

Michelle, our media mail doesn't go to Canada.  This isn't about PBS, it's the cost set down by the USPO. I believe the cheapest cost to mail a small book to Canada is $4.99. The price goes up from there as the book weight goes up. My family is all in Canada and a long time ago I stopped mailing books to them.  

In fact, many if them come to the states to buy their books. My cousin was down here a couple months ago and went home with lots of books because of both the cost of the book to buy up there and the cost of ordering and having it shipped. 

Both Canada Post and sending into Canada are stupidly expensive. I'm glad we have stayed US only. 

If Canada and the U.S. could come to an agreement to have the media mail rate apply to both countries, I'd love to ship to Canada; but until then...

Hi ! I am from Quebec - Canada but lucky enough to live 5 minutes away from the US border ! I rent a PO Box

and this way - I can be a member of paperbackswap !

Perfect solution, Tina!