If you are an immigrant living in California, you may wish to apply for U.S. citizenship at some point. You receive many benefits from becoming a naturalized citizen, not the least of which is that you no longer need worry about your immigration status or if all your papers are up-to-date and otherwise in order. As the U.S. Citizenship and Immigration Services explain, however, in order to become an American citizen, you must successfully pass a naturalization test.
The first step you must take in your naturalization process is to interview with a USCIS officer. (S)he will ask you questions about your background and your naturalization application which you must answer truthfully. Under most circumstances this interview will be in English, so you need to have a basic command of the English language so as to be able to understand the questions and respond appropriately. Then you must take both an English test and a civics test. To prepare for these tests, you can attend naturalization classes and/or study the numerous study materials available.