Can a U.S. Broker, Lender, etc., do business in Canada?

[N/A N/A]

My question is: Can a U.S. Broker, Lender, etc., do business in Canada? ...and if so, who can, and how does one go about it? I've been seeing quite a bit of positive media lately, re: the real estate market in Canada. I'm located in the New York City area, and capable of doing business in all 50 U.S. states. I wanted to explore the idea of expanding my market place to cover Canada as well.

If anyone could please educate me as far as what is allowed, and how I go about doing it, I would really appreciate it.