A criminal record can make you forbidden to enter the United States. A criminal history that includes crimes of moral turpitude, terrorism, prostitution, drugs and gambling will make you ineligible to enter the country, let alone apply for citizenship. Being eligible to apply for citizenship means you are inside the United States as a legal permanent resident, and have been for years. If you were convicted of a crime and you were not deported, the crime will not likely make you ineligible for naturalization. Use full disclosure when filling out form N-400, Application for Naturalization.
Visit the website of The United States Citizenship and Immigration Service (uscis.gov). Click on "Citizenship Through Naturalization" in the middle of the page under the larger heading of "Citizenship."
Click the link entitled "Form N-400, Application for Naturalization" at the top of the page. Print out the PDF files for the N-400 application, instructions and the checklist of required documents.
Gather the required documents. These may include proof of permanent residency status, marriage licenses, proof of military service, proof of physical residence within the United States and proof of port of entry.
Read the instructional booklet, and fill out the application fully. Use black ink and provide an "N/A" for questions that you cannot answer.
Use full disclosure and honesty when filling out the criminal records section. Provide police clearances from other countries and use the free-form space to explain your actions. The FBI will run a criminal backgrounds check using your fingerprints and will be able to see your entire criminal history, including expunged, sealed or set aside crimes.
Provide records of your criminal activity including a certified copy of the arrest report, court disposition and sentencing. You may provide circumstantial evidence shedding light on the circumstances of the crime that you would like USCIS to consider. Your criminal history may bar you from naturalization, temporarily bar you from naturalization or it may not be a factor.
Mail your application into the appropriate lock-box facility. Include the documents and a U.S. Postal money order for $680 made payable to the Department of Homeland Security.
Wait for a response from the government and cooperate. You may be ineligible, and USCIS may take action against you. You may be conditionally accepted and directed to attend an interview.
Go to your interview to take a verbal citizenship test consisting of 10 questions; you must get six questions correct. Prove your English language proficiency by answering the test questions in English. Take an oath in front of a judge and receive your citizenship certificate.