The process for applying for loans depends on your School. Some Schools have separate financial aid operations, so you need to make sure that you apply through the correct Financial Aid Office. Follow the link listed for your School to learn about the application requirements and specific loan programs.
Business: GSB Financial Aid Office
Earth Sciences, Education, Engineering, Humanities & Sciences, Medicine (PhD, MS): Central Financial Aid Office, Applying for Aid
Medicine (MD): Med School Financial Aid Office