POWERLIFTING has been part of the Summer Paralympics since 1964, when it was known as weightlifting; women's events were added in 2000. At the London 2012 Paralympics, 120 men and 80 women will be competing in 20 medal events at the ExCeL venue from August 30 through September 5. There are no classifications based on particular types or degrees of impairment. All athletes compete by weight class alone: -48 kg, -52 kg, -56 kg, -60 kg, -67.50 kg, -75 kg, -82.50 kg, -90 kg, -100 kg, and +100 kg for men, and -40 kg, -44 kg, -48 kg, -52 kg, -56 kg, -60 kg, -67.50 kg, -75 kg, -82.50 kg, and +82.50 kg for women.
According to the description on the site of the International Paralympic Committee, "At first, only men with spinal-cord injuries could participate, but today the competition is open to all athletes with cerebral palsy, spinal-cord injuries, lower-limb amputees and others who meet the minimal disability criteria. ... The bench press is the sport's single discipline, with 10 different categories based on body weight. The athletes are given three attempts and the winner is the who lifts the highest number of kilograms."
You can read more about Paralympic Powerlifting on the site of the 2012 London Paralympics.