[1] DeMarco started working at Bell Telephone Laboratories in 1963, where he participated in ESS-1 project to develop the first large scale Electronic Switching System, which became installed in telephone offices all over the world.
[2] Later in the 1960s he started working for a French IT consulting firm, where he worked on the development of a conveyor system for the new merchandise mart at La Villette in Paris, and in the 1970s on the development of on-line banking systems in Sweden, Holland, France and New York.
[4] In January 1978 he published Structured Analysis and System Specification,[5] a major milestone in the field.
[citation needed] DeMarco has lectured and consulted throughout the Americas, Europe, Africa, Australia and the Far East.
a principal of the Atlantic Systems Guild, and a fellow and Senior Consultant of the Cutter Consortium.