If you are already in the US and want to change the purpose of your visit, you must submit a request with the US Citizenship and Immigration Services (USCIS) while your authorized stay is still valid. For example, you may have entered the US as a tourist but you want to stay to attend school. Apply as soon as you decide you want to change your nonimmigrant category. Until you receive authorization to change your status, do not change your activity in the United States. If you do not comply with this and start attending school, for example, you may risk deportation and be barred from returning to the US.