Apply to the Department of Electrical Engineering and Computer Science, the Department of Mathematics, the Computation for Design and Optimization Department, or the Department of Aeronautics and Astronautics by following the links on the MIT Graduate Admissions page provided in Resources. Create a login name and password for the department in question and fill out the application tailored (and sent) directly to that department.
Apply to Sloan School of Management programs in Biomedical Enterprise, Leaders for Global Operations, Master of Finance, Master of Science in Management Studies, MBA, MBA for Executives, System Design and Management, and any Ph.D. programs housed in the department by following the link to the Sloan School of Management in Resources. Apply via the online link next to the program (when available) or print out a paper application to mail in.
Apply to all other programs through the CollegeNet portal. Read the associated "Form Instructions" on how to use the application interface. Create an account and complete your application.
Refer to the application guidelines for your program to determine what other materials need to be submitted to MIT. This will often include the transcript for your undergraduate degree, your GRE scores and letters of reference.