Yes, you need a permit to backpack in Lassen Volcanic National Park. A wilderness permit is required for all overnight stays in the backcountry. You can obtain a free wilderness permit at the Loomis Museum, Kohm Yah-mah-nee Visitor Center, or any self-registration station at park trailheads. During the peak season (June through September), a limited number of permits are available for reservation online, while the remaining permits are available on a first-come, first-served basis. For more information on backpacking and permits in Lassen Volcanic National Park, visit the Hipcamp Lassen Volcanic National Park page and the official National Park Service website.