Immediately after completing his master’s degree at Purdue in 1960, Paul McEnroe began what was to be a 23-year career at IBM. In the late 1960’s, he led and contributed technically to the team that developed the Universal Product Code, commonly known as "the bar code." The team also developed associated technologies including IBM’s first intelligent terminal, custom chip, and distributed system. Later he was responsible for the development of "The Token Ring" Local Area Network and served as IBM’s group director of Systems Development. In his last IBM assignment, he was director of the Raleigh Laboratory which developed IBM’s communications products.

In 1984, McEnroe became president of Trilogy Systems Corporation where he led the development of copper-polyimide multichip module technology. He negotiated a merger of Trilogy with Digital Equipment Corporation and continued working for Digital until his retirement in 1992. He then became president of The Pathway Group, a Menlo Park consulting firm. Realizing a life-long dream, McEnroe now devotes his time to horse breeding and cattle ranching at his Rancho La Purisima in the Santa Ynez Valley.

McEnroe is chairman emeritus and a director of the California Engineering Foundation, a member of the University of Dayton Engineering Advisory Board, a Trustee of St. John’s Seminary and Seminary College in Camarillo, and a director of the Santa Barbara County Cattlemen’s Association. He is a Senior Member of the Institute of Electrical and Electronics Engineers and a former member of California’s Blue Ribbon Committee on Educational Technology.