QUOTE(Reba @ Nov 8 2007, 08:34 AM)

If you are a Canadian citizen, you are required to declare yourself as a Canadian citizen when you enter the country. That means presenting your Canadian passport at the border entry, not your US passport. Same goes for US, if you are an American citizen, you are required to declare yourself as an American when entering the country, and show your US passport. Which means of course, if you are traveling between the 2, you must carry both.
There are pros and cons to dual citzenships, know what they are before you make a final decision.
Actually if you are duel you can claim either citizenship. There is no stipulation you "must" present the Canadian passport upon arrival to Canada unless you are living in Canada as a duel citizen. Many people do bring both, but many do not. In fact many dual citizens no longer apply or have Canadian passports anymore.
For me Canada may view myself as a Canadian citizen. I consider myself as an American and so does the US. So I will present myself as a US citizen. The only difference is yes theoretically I could be denied like any other person and I would not have any legal basis to enter the country as if I would if I presented myself as Canadian, but that is about it. I however am not worried about being denied entry into Canada at all...