Dual citizenship is when a person is legally a citizen of two countries at the same time. They will have legal rights and obligations in both countries. While dual citizenship gives certain advantages, such as easy residency in multiple countries and access to government programs, there are many legal considerations that can make life more complicated. For example, the dual citizen may have tax obligations in more than one nation, or may need to fulfill residency requirements between two homelands. Not all countries allow dual citizenship, so you must check with the countries you are seeking citizenship.
The United States does not formally recognize dual citizenship. However, it also has not taken any stand against it, either legally or politically. Typically, no American will forfeit his or her citizenship by undertaking the responsibilities of citizenship in another country. This is true even if the responsibilities include traveling with a foreign passport, voting in another country's election, or running for and/or serving in public office of another country. In most cases, it is unimportant to U.S. authorities whether another country also claims you as a citizen.
Although it's rare, some countries will revoke a national's citizenship when citizenship is acquired elsewhere. Other countries require renunciation of any prior citizenship as a condition of naturalizations. It is important to carefully read all of the rules of citizenship for each country.
If you hold dual citizenship with the United States and another country, it's important for you to understand the legal rights and obligations that you may have as a result. To learn more, and to discuss the specifics of your situation, it's a good idea to contact an experienced immigration attorney near you.