If you are applying to the US then you will ask two teachers to write for you. The only exceptions would be if you are applying to some Art, Drama or Music related programs in addition to other more academic programs or if you are registering on NCAA for athletic reasons. If that is true for you then please talk with your counselor about requesting a third letter. Universities want to hear from teachers that have taught you recently (Grade 11-12) and they generally prefer letters from core teachers (e.g. math, science, social science/history, English, and/or foreign language. Sometimes (really not often) do universities specify what subject teachers they want to hear from (Math and English at MIT for example) and then you don't really have a choice anymore. If you are applying to universities in Australia and/or UK only then you don't need to ask any teachers to write for you. If you are applying to Canada only then you can ask for one letter (some programs do require a letter). If you are applying to any university that have a specific recommendation letter format/form that they want your teacher to use then please contact your counselor and we will guide you through that process. Please contact your counselor if you are still confused about what teachers to approach with your letter request. Here is more information on how to decide on which teachers you want to ask to write for you from Vanderbilt University. Most other US universities would give you the same or similar guidelines.