A private ceremony billed as a "night of remembrance" starts at 5 p.m. Colorado's governor and Aurora's mayor are expected to attend.
Officials distributed 2,000 tickets to victims and their families. Some families, however, are boycotting the event.
"The fact that we were being used as pawns," said Jessica Watts, cousin of a shooting victim. "That they were using us as momentum for their public ticket sales by telling the public, 'well look, the family members of this massacre came back, and it's okay for them to come back and it's going to be okay for you guys too.'"
Some victims say it's important to reclaim the theater as part of the healing process.
The theater will reopen to the public a week from Friday.