Posted By Frank Cooper Nigel, HEINRICH'S (your spelling is wrong!) theory is based on a chain or sequence of events that can be listed in chronological order to show the events leading up to an accident. event a - event b - event c - accident - effect. Each event may have more than one cause. Heinrich states that the occurrence of an injury accident invariably results from a sequence of factors culminating in the injury itself. He states five factors or stages in the accident sequence as follows: a) Ancestry or social environment leading to: b) fault of person, constituting the proximate reason for c) an unsafe act and/or mechanical hazard, which results in d) the accident, which leads to e) the injury. It's commonly known as the "Domino Theory". Heinrich said that if you can remove c) you will prevent the accident from happening. Hope this helps, Frank Cooper