Le Grand Défi Solidaire is an autumn charity running and walking event held at the Parc de Sceaux, located in Hauts-de-Seine, south of Paris. The event supports research into multiple sclerosis, offering various participation options: runners can select a 5 km or 10 km course, walkers have 2.5 km or 5 km options, and teams can complete the 10 km as a 2 x 5 km relay.
The courses are situated within the Parc de Sceaux, a public park featuring paths winding between its lake and wooded sections. Dedicated short distances are available for children and juniors, including 1 km and 2.5 km. Supporters are integrated into the event's activities. The event also provides a virtual race option and on-site activities accessible to everyone, allowing individuals to contribute by running, walking, relaying, bringing children, or cheering for participants who support the 140,000 individuals in France affected by multiple sclerosis.