Online registration is required to compete in the Mercer Science and Engineering Fair. This can be done at any time before the fair deadline, but it is advantageous to do so when the application forms need to be initially filled in. If you enter the information online, you can download this information and the blank form files, and then print the forms with this information. These forms still need to be signed and mailed in.
If you do not use the online registration system before your experiments begin, make sure that you print out the blank ISEF forms and get them approved and signed.