To obtain the French citizenship, you must prove your level in French by taking an accredited test such as the “Test de Connaissance du Français” (TCF).
Alliance Francaise San Francisco is an official test center for the TCF. You can find more information here: http://afsf.com/exam-center/tcf/
Common reference levels
The Common European Framework of Reference for Languages (CEFR) divides learners into three broad divisions that can be divided into six levels; for each level, it describes what a learner is supposed to be able to do in reading, listening, speaking and writing. These levels are:
These descriptors can apply to any of the languages spoken in Europe, and there are translations in many languages.
Alliance Française has stated students can expect to reach CEFR levels after the following cumulative hours of instruction: A1 60–100, A2 160–200, B1 360–400, B2 560–650, C1 810–950, C2 1060–1200.