Citzenship Through Birth
  First, the easiest way to become a citizen of Ireland is to be born here, with at least one parent being an Irish citizen or entitled to Irish citizenship. However, having a child born here no longer confers automatic rights of residency to the foreign-born parents. In recent years, Ireland was flooded by economic refugees—and many women took advantage of the country's liberal laws by giving birth as quickly as possible. As a result of a Supreme Court decision, the immigration division no longer accepts applications for residency from individuals based purely on their parentage of an Irish-born child.

Citizenship Through Descent
  If either parent was born in Ireland, you're automatically deemed Irish by right of birth (the jus sanguinis principle). There is no need to register a claim or even to take up residency to acquire citizenship. To obtain an Irish passport, all you have to do is to submit the necessary documentation to the nearest Irish embassy or consulate. Along with passport photos, you'll be asked to produce your own birth certificate, your parents' birth certificates, and their marriage certificate.
  Again, you don't have to be resident in Ireland to claim citizenship through a grandparent. However, the procedure is a little different and needs to be undertaken by what is known as “foreign birth registration.” Applications are processed through the local Irish embassy or consulate, or (once you are resident in Ireland), through the Department of Foreign Affairs.
  A great deal of paperwork will need to be produced, both the original certificates and two copies of each document. You'll need your own birth certificate, the birth certificate of the parent you are claiming Irish ancestry through, and also that of your Irish-born grandparent. If his or her birth certificate is unobtainable, a baptismal certificate may be acceptable, though this is likely to slow down the process somewhat. You'll also need to produce marriage certificates for yourself (if applicable), parents, and grandparents. Death certificates are also required if a grandparent or the relevant parent is deceased.
  Along with two passport-sized photos, you must also submit a photocopy of a current passport (if you have one), and photocopies of three more forms of identity such as a driver's license, social security number ID card, pay slips, or bank statements. You may have heard that Irish citizenship can be claimed through a great-grandparent. This was so until 1984. Unfortunately, the legislation was altered and it's no longer possible for great-grandchildren to benefit from the jus sanguinis principle.

Citizenship Through Marriage
  Marriage is another route to Irish citizenship. It used to be that if you had been married to an Irish citizen for three years, you could also claim citizenship. However, the law has been changed. Now any nonnational who married an Irish citizen on or after November 30, 2002, can apply for citizenship only through the naturalization process.

Citizenship Through Naturalization
  Ireland's Department of Justice handles applications for naturalization and citizenship is granted at the minister's “absolute discretion.” It's a slow process and generally takes between 18 and 24 months before any decision is reached. To be considered for Irish citizenship, the following criteria have to be satisfied: The applicant is resident in the state and is 18 years of age or older. During the preceding nine years, the applicant must have lived legally in the state for five of those years. The last of those five qualifying years must have been one of continuous residence, though an absence for vacations or business won't generally be regarded as a break in residence.
  Applicants must satisfy the minister of their good character and also of their intention to live in Ireland after naturalization. The following documentation has to be submitted with an application, both the originals and a photocopy of each:
 • A passport
 • Garda Síochána certificate of registration (green residency permit book)
 • Birth certificate with a certified translation if not in English
 • If applicable, a marriage certificate-again with certified translation if necessary
 • Statement from the revenue commissioners that all due taxes have been paid
 • Depending on circumstances, details of personal tax, company tax, PRSI contributions, and VAT payments
 • Documentary proofs of financial status such as bank or building society statements
 • If applicable, pay slips or statement of earnings from an employer
Should the minister grant your application, you'll be required to stand in open court before a district court judge and make a declaration of fidelity to the nation and loyalty to the state.
For more information contact the Department of Justice, Immigration and Citizenship Division.

HOLDING DUAL NATIONALITY

  Unlike in some European countries, taking up Irish citizenship doesn't require renouncing another citizenship. Ireland's Department of Foreign Affairs has no objection to anyone's holding dual citizenship, but it does advise individuals to clarify the position with home governments first.
  Looking at it from the reverse angle, the U.S. government will not deem you to have committed an expatriating act simply by becoming a dual national. To lose your legal status as a U.S. national, you would need to have committed treason or have formally renounced your citizenship.
  One specification is that you are required to use your U.S. passport when leaving or entering the United States. However, even if you decide to use your Irish passport when traveling elsewhere, you can still call on the assistance of U.S. embassies and consulates. Another point to note is that the U.S. government still expects its overseas citizens to file tax returns, even if no tax is payable. Even so, one congressional report estimated that around 61 percent of Americans living abroad are flouting this rule. In an attempt to keep track of its wayward citizens, every U.S. national applying for a passport is supposed to file an IRS information report listing foreign residences and other details that the taxman may find interesting.

Rights and Obligations of Citizenship
  The main obligation for Irish citizens resident in the state is the requirement to undertake jury service if called upon to do so. As a citizen you'll have full voting rights which, for others, depends on status.
  At present, only Irish citizens can vote in presidential elections or a referendum. The only resident foreigners entitled to vote in elections to the Dáil (the Irish Parliament) are U.K. citizens—that's because Irish citizens living in the United Kingdom also have the right to vote there. Voting in elections to the European Parliament is open to any resident holding citizenship of an EU member state.
  However, you don't need to hold Irish or any other kind of EU nationality to vote in local elections—you simply need to be resident here and have your name on the electoral roll. Those who are entitled to vote only in local elections have the letter “L” after their names on the register.
  A new register of electors is compiled each year. To get on the register, either contact your local council offices or fill in a form at the post office. The process of compiling the register starts in September/October and comes into effect the following February. To make sure you're on the electoral roll, you can check the draft register that is published on November 1. It's available for inspection in post offices, libraries, Garda stations, and local authority offices.