Question: I've just received my green card. If I decide to file for U.S. citizenship, do I risk losing my Canadian citizenship?
Answer: Generally, citizens of other countries may retain their original citizenship when they naturalize in the United States provided their government permits the dual-citizenship. The current Citizenship Act does allow Canadian citizens to acquire a foreign nationality without automatically losing their Canadian citizenship. See Dual Citizenship.
Similarly, the U.S. Immigration and Nationality Act does not expressly prohibit dual citizenship. While recognizing the existence of dual citizenship and permitting Americans to have other citizenships, the U.S. Government does not endorse dual citizenship as a matter of policy because of the problems that it may cause. Claims of other countries on dual-national U.S. citizens often place them in situations where their obligations to one country are in conflict with the laws of the other. As result, U.S. citizenship may be lost as result of certain voluntary actions accompanied by intent to relinquish U.S. citizenship. See Possible Loss of U.S. Citizenship and Dual Nationality.