Joining the Mergenthaler Linotype Company in 1959 as design director, Parker went looking for an adaptable European font that would work at many different weights. He particularly liked the new Swiss style of letter design, in which, Parker said, «you draw the counters and let the black fall where it will.» Parker soon discovered Neue Haas Grotesk, a sans-serif typeface created by Swiss designers Max Miedinger and Eduard Hoffman of the Haas Type Foundry.

Designed as a clear, neutral typeface that could be used in a wide variety of settings, Neue Haas Grotesk had one problem: it wasn't designed to be used in a Mergenthaler Linotype hot metal typesetting machine—the industry standard machine, created by Mergenthaler Linotype, for printing newspapers, magazines and posters. As such, Parker and his team took Haas' original drawings and began reworking them to work on Linotype's machines. The modified design eventually became known as Helvetica.via Fast Co.Design.