Guaranteed entry through a charity means you can secure your spot in a major marathon—without needing to qualify or secure a bib through the lottery—by joining an official charity team. Charities like the Children’s Brain Tumor Project Foundation receive a limited number of race bibs from event organizers, and runners who commit to raising a set fundraising minimum earn one of these guaranteed entries. It’s a meaningful way to participate in world-class races while directly supporting life-changing research.