A large number of technical support personnel were required to respond to the Three Mile Island Unit 2 (TMI-2) accident of March 28, 1979. Under the leadership of General Public Utilities personnel, onsite (round-the-clock shift) technical support began the evening of March 29 and within a week the TMI Recovery Organization incorporated all of the essential technical capability to implement the Base Plan for Cooldown, manage the radioactive waste problem, and begin the steps toward long-range plant recovery. The number of support personnel grew rapidly from the initial 10 to 20 to almost 2000 by mid-April. All segments of the industry and government organizations responded to the calls for assistance. Many complex problems were identified, analyzed, and solved during the initial recovery operations, e.g., estimating core damage, removing decay heat from the core using forced and natural circulation, and elimination of the hydrogen bubble.