The improved load-bearing equipment (ILBE) is a United States Marine Corps program that had included individual load carriage equipment, individual hydration systems, and individual water purification.

Since the rucksack was the first component of the program to be issued to Marines, the rucksack is commonly referred to as simply the ILBE. The ILBE rucksack was designed to replace the long existing all-purpose lightweight individual carrying equipment (ALICE) packs and newer modular lightweight load-carrying equipment (MOLLE) packs.

On August 14, 2002, the US Marine Corps presented a Commercial Area Announcement (CAA), soliciting designs for an Improved Load Bearing Equipment (ILBE) system. The Marine Corps Systems Command (MCSC) determined the top two designs of those submitted from the commercial vendors were those of Bianchi (Gregory) and Propper International (Arc'teryx).

Arc'teryx's design weighed 8 pounds (3.6 kg) and carried 5,000 cubic inches, while the Gregory design weighed 10 pounds (4.5 kg) and carried 4,520 cubic inches. From January 2003 through June 2003, a Field User Evaluation was conducted, seeing 900 systems from each vendor (Gregory and Arc'teryx) tested across Marine units. The US Army Research Institute of Environmental Medicine (USARIEM) performed a series of biomechanical tests to evaluate the two selected packs and to compare them to the existing MOLLE packs.

Parts of the ILBE system were derived from items in Arc'teryx's Law Enforcement and Armed Forces (LEAF) product line.^{[citation needed]} The finalized ILBE system was designed by Arc'teryx, and was later manufactured by Propper.

In January 2004, ILBE began the process of being fielded.

In 2005, ILBE's initial operational capability (IOC) was reached, signifying the initial units who received ILBE had received necessary training on the system and that its repair parts were available.

In April 2006, ILBE had a monthly production rate of 4,700/month.