I am a U.S. citizen with parents who are U.S. citizens.  All four of
my grandparents are deceased however, they are all Mexican Nationals
(Mexican Citizens).

Is it possible to obtain dual citizenship based on my grandparents
citizenship?  I have been given different advice however, I am not
sure what is the correct answer.

Does anybody know the answer to this question?  Or where I can find the answer?

Thank you

After doing some research i have come across the following information
which i hope can help you.

http://travel.state.gov/travel/cis_pa_tw/cis/cis_1753.html

gives information on the state of dual citizenship.

"The concept of dual nationality means that a person is a citizen of
two countries at the same time. Each country has its own citizenship
laws based on its own policy.Persons may have dual nationality by
automatic operation of different laws rather than by choice. For
example, a child born in a foreign country to U.S. citizen parents may
be both a U.S. citizen and a citizen of the country of birth.

A U.S. citizen may acquire foreign citizenship by marriage, or a
person naturalized as a U.S. citizen may not lose the citizenship of
the country of birth.U.S. law does not mention dual nationality or
require a person to choose one citizenship or another. Also, a person
who is automatically granted another citizenship does not risk losing
U.S. citizenship. However, a person who acquires a foreign citizenship
by applying for it may lose U.S. citizenship. In order to lose U.S.
citizenship, the law requires that the person must apply for the
foreign citizenship voluntarily, by free choice, and with the
intention to give up U.S. citizenship.

Intent can be shown by the person's statements or conduct.The U.S.
Government recognizes that dual nationality exists but does not
encourage it as a matter of policy because of the problems it may
cause. Claims of other countries on dual national U.S. citizens may
conflict with U.S. law, and dual nationality may limit U.S. Government
efforts to assist citizens abroad. The country where a dual national
is located generally has a stronger claim to that person's allegiance.

However, dual nationals owe allegiance to both the United States and
the foreign country. They are required to obey the laws of both
countries. Either country has the right to enforce its laws,
particularly if the person later travels there.Most U.S. citizens,
including dual nationals, must use a U.S. passport to enter and leave
the United States. Dual nationals may also be required by the foreign
country to use its passport to enter and leave that country. Use of
the foreign passport does not endanger U.S. citizenship. Most
countries permit a person to renounce or otherwise lose citizenship.

Information on losing foreign citizenship can be obtained from the
foreign country's embassy and consulates in the United States.
Americans can renounce U.S. citizenship in the proper form at U.S.
embassies and consulates abroad."

If you wish to call someone from the USA about dual citizenship and
its risks you may be able to speak to someone in the know from one of
these telephone numbers.

Primarily "Latin America and the Caribbean Division at (202) 647-5118;"

"Counsel representing persons in matters related to loss of U.S.
nationality may also address inquiries to Director, Office of Policy
Review and Inter-Agency Liaison, Overseas Citizens Services, Room 4817
N.S., Department of State, 2201 C Street N.W., Washington, D.C. 20520,
202-647-3666."

This page gives information on loss of american citizenship if you
claim a dual nationality.

http://travel.state.gov/law/citizenship/citizenship_778.html

"DUAL NATIONALITY

Dual nationality can occur as the result of a variety of
circumstances. The automatic acquisition or retention of a foreign
nationality, acquired, for example, by birth in a foreign country or
through an alien parent, does not affect U.S. citizenship. It is
prudent, however, to check with authorities of the other country to
see if dual nationality is permissible under local law. Dual
nationality can also occur when a person is naturalized in a foreign
state without intending to relinquish U.S. nationality and is
thereafter found not to have lost U.S. citizenship the individual
consequently may possess dual nationality. While recognizing the
existence of dual nationality and permitting Americans to have other
nationalities, the U.S. Government does not endorse dual nationality
as a matter of policy because of the problems which it may cause.
Claims of other countries upon dual-national U.S. citizens often place
them in situations where their obligation to one country are in
conflict with the laws of the other. In addition, their dual
nationality may hamper efforts to provide U.S. diplomatic and consular
protection to them when they are abroad."

This website is the american consulate in Mexico (ciudad juarez) and
may have information about dual citizenship and how to obtain it. You
can contact them on the following phone numbers.

http://ciudadjuarez.usconsulate.gov/wwwhhow.html

General Information
Phone

Phone: (656) 611-3000
(This phone number is NOT for visa information)
If calling from the U.S. dial 011-52 before the number

Immigrant Visas From the U.S: 1-900-476-1212

Unfortunately i do no speak Spanish so i am unable to understand this
website however i believe that it would be able to give you the
information regarding obtaining citzenship based on grandparents.

*IT IS IN SPANISH*

http://portal.sre.gob.mx/washington/index.php?option=displaypage&Itemid=59&op=page&SubMenu=

http://www.embassyofmexico.org/

This page has information on the requirements of obtaining a mexican passport.
http://www.consulmexny.org/eng/passport.htm

The following page has the following information
http://www.mexperience.com/liveandwork/immigration.htm#Citizen

"Can I be granted Mexican Citizenship?

Acquiring Mexican Citizenship is an involved process, and it is not
easy to do.   As a minimum, you must have been living in Mexico for 5
years (2 years under special circumstances) and have resident status. 
  Marriage to a Mexican national may allow Citizenship without the
residency requirement.    For matters concerning the acquisition of
Mexican Citizenship, seek professional advice and contact your local
Mexican Consulate."

A list of Mexican Consulates in the USA and Canada is available here.
You will be able to call your local consulate and speak to them
directly about how to obtain the Dual citizenship or become a full
Mexican Citizen.
http://www.mexonline.com/consulate.htm

I hope this helps, if i can be of any further assistance do not
hesitate to to leave a comment.

-- keystroke-ga

---

Clarification of Answer by keystroke-ga on 26 Jul 2006 02:25 PDT

To find out if you are able to get dual citizenship of the USA and
Mexico speak to both the USA and Mexican consulates as listed in my
reply, they can give you a definitive answer.

--Keystroke-ga

thank you for you answer however, was looking for more specific info. 
I'm still wondering:  Can I obtain a dual citizenship based on my
grandparents?

The answer is correct, but although the US does not encourage dual
citizenship, a Supreme Court decision ca. 30 years ago clarified that
applying for and receiving a new citizenship does not automatically
result in the loss of US citizenship.

In the texts quoted, this is hidden in this sentence:

"In order to lose U.S. citizenship, the law requires that the person
must apply for the foreign citizenship voluntarily, by free choice,
and with the intention to give up U.S. citizenship."

"... and with the intention to give up U.S. citizenship."

Thank you for mentioning this, it is something that has been playing
on my mind ever since I wrote this answer. I believed that applying
for a second citizenship did NOT automatically lose your U.S.
citizenship and thought I should make this clearer. Thank you for
making it clearer.

I don't know if you can attain citizenship based on your grandparents.
 However, the information below indicates it can be based upon Mexican
born parents.

One needs to call a Mexican consulate to obtain a definite answer.

http://www.aztlan.net/dualcit.htm
MEXICAN DUAL NATIONALITY PR0GRAM

DECLARATION OF MEXICAN NATIONALITY (Mexican Citizenship)

The Mexican Government is granting the opportunity to people of
Mexican decent who are naturalized citizens or citizen by birth of
another country, to recover their Mexican Nationality.

To obtain the Declaration of Mexican Nationality, the interested party
must meet the following:
REQUIREMENTS

   1. Be at least 18 years of age and of sound mind.


   2. Complete the application at the Mexican Consulate.


   3. Present the following documents in original and two photocopies:


         1. If the person was born in United States:


                * A Certified copy of the Birth Certificate,
apostilled by the Secretary of State of the issuing authority.


                * Original or certified copies of the Mexican father
or mother's birth certificate.


         2. If the person was born in Mexico


                * Original or certified copy of the birth certificate.


   4. Married women need to present the marriage certificate.


   5. Document that proves the U.S. citizenship (i.e. passport or
Certificate of Naturalization).


   6. Official picture ID (i.e. Driver's license, passport, California ID, etc.)


   7. Two-passport size photos.


   8. This is a toll free process; the Mexican Consulate is the only
autorizated institution to complete it. Upon receiving the Declaration
of Mexican Nationality, a $14.00 fee will be assessed.