After receiving the primary centralized application, most schools will send students a secondary application or invite them to open it on-line. Some schools will do an initial screening of the AMCAS application and will only invite a segment of their applicant pool to complete the secondary application.
The secondary applications vary considerably from school to school. Almost all require additional money in the form of secondary application fees; most of them require additional information and supplementary essays, often with more specific guidelines than the preliminary applications. Students should complete secondary applications promptly. An application is not complete without the secondary, and applications will not be reviewed until they are complete. Students are encouraged to keep copies of all their secondaries, in case schools lose or misplace the originals.