In order to become a U.S. citizen, you need to satisfy the various requirements described in the article Who Can Apply for U.S. Citizenship. Most people also need to pass tests on their knowledge and understanding of:
Although those requirements sound broad, you won't really have to learn all there is to know about the United States and its primary language. Let's look more closely at what you will, in fact, have to study and learn.
U.S. Citizenship and Immigration Services (USCIS) has prepared a list of potential questions for the history and government exam. These, with their answers, are published in advance for anyone to see. You will have to memorize the answers to these questions—ideally all of them—but you will really need to answer only a limited number of the questions correctly in order to pass.
The trouble is, you can't know in advance which questions you'll be asked—the USCIS official who interviews you gets to choose. (It's an oral exam, given during your naturalization interview.)
The civics test has a total of 100 questions. In order to pass, you'll need to correctly answer only six out of ten questions that the examiner asks you.
(Although USCIS had planned to change this in 2021, such that applicants would need to study 128 questions and correctly answer 12 out of 20 questions in order to pass, these plans were reversed under the Biden Harris administration).
See the Study Materials page of the USCIS website to find the applicable questions and various means of studying them.
There are some people who, for reasons of age or disability, will find it nearly impossible to learn the answers to these questions. Some exceptions can be made in these cases, as described next.
If you are at least age 65 and have lived in the U.S. as a permanent resident for at least 20 years (these don't need to be continuous years) when your file your citizenship application, you can take an easier version of the history and government exam. This is commonly referred to as the "65/20 exception."
You will have to study only 20 questions (the ones with asterisks on the main list of questions). You'll be asked ten of the questions and will need to answer six correctly in order to pass. Plus, you can take the test in your native language if you need to. You'll have to bring your own interpreter though.
If you have a physical or mental disability that prevents you from learning the required concepts of U.S. history and government, you might qualify for a waiver. You'll need to have your doctor fill out a form (N-648) explaining exactly what your disability is and why it prevents you from learning concepts of U.S. civics and government.
You must show that you can speak and read in English. You will need to demonstrate your English skills at your citizenship interview. The USCIS officer who interviews you will of course talk to you in English, and observe how well you respond to questions and instructions. The officer will also ask you to read a short passage and to write a sentence that he or she says aloud (dictates) to you.
To focus on the key vocabulary, see the Study Materials page of the USCIS website.
If you aren't already comfortable with the English language, taking a class at a local adult school could help.
Two separate rules allow older people to avoid the English requirement. If you are at least age 50 and have lived in the U.S. as a green card holder for at least 20 years when you file your citizenship application, you can have the entire citizenship interview conducted in your native language. (This is commonly known as the "50/20" waiver.) Your 20 years of residence do not need to have been continuous. If you have been away for short periods (fewer than six months at a time, to be safe), that is acceptable, so long as your total time living in the United States reaches 20 years.
The second rule, known as the "55/15" waiver, applies as follows. If you are at least age 55 and have lived in the United States as a green card holder for at least 15 years when you file your citizenship application, you can have the citizenship interview and exam conducted in your native language. Your 15 years do not need to have been continuous.
If you qualify to have the interview done in your native language, you'll have to bring your own interpreter—USCIS won't provide one for you.
If you have a physical or mental disability that prevents you from learning English—for example, an illness that requires regular medication that makes you severely drowsy, a developmental disability, or deafness—you might qualify for a waiver of the English requirement. In such a case, you would be allowed to have the citizenship interview done in your native language.
You can't just request this waiver; a doctor must fill out a form (N-648) explaining your disability and why it prevents you from learning English.
For more information on naturalizing in the U.S., see Becoming a U.S. Citizen; A Guide to the Law, Exam, and Interview, by Ilona Bray, J.D.