An experiment invitation e-mail includes a personalized link which leads to the participant's experiment registration page. This page consists of three parts:

• a list of invitations (that is, future sessions for all experiments the participant has been invited for but has not enrolled in yet, and for which the enrollment period has not expired yet, see also section Creating sessions);
• a list of current enrollments (that is, future experiment sessions the participant has signed up for); and
• a list of previous enrollments (that is, sessions a participant was signed up for, including a summary of completed sessions and the subject's respective participation status for each past enrollment, see section Completing and closing a session).

While the two latter only have informational character, the first list features small Sign up buttons on the right side. If a subject clicks on one of these buttons, she has to confirm once more, and then signs up for the respective session. A text on the page may inform the participant about the binding character of the session enrollment. Upon enrollment, a confirmation e-mail is sent to the participant's e-mail address to inform him about the successful enrollment, and remind him of date, time and location of the session. The subject will also receive a reminder email (e.g., 48 hours before the session starts), the exact time of which can be specified on the administration page for the session (see section Creating sessions). After enrollment, the respective session will be listed in the “list of current enrollments” (see above).

The laboratory management may enable an ORSEE feature that allows subjects to cancel their session enrollment (with a cancellation deadline set as a system-wide policy). While this may increase flexibility for subjects, it may have adverse effects on the variability of subject numbers, in particular when subjects cancel late. Not allowingself-cancellation, combined with the reputation system, may encourage subjects to check more thoroughly whether they are available for the time of the session or not.

The enrollment page is also available as a separate version for mobile devices. It allows the same functionality for enrollment, listing of current and past enrollments, and cancellation as described above.