[5][6][7] The firm was established as The Parthenon Group LLC in 1991 by former Bain & Company directors William "Bill" Achtmeyer and John C. Rutherford.

The firm advises top management (C-Suite) on strategic issues across a broad range of industries including Private Equity, Consumer Products, Education, Financial Services, Healthcare, Information & Media, Advanced Manufacturing, Life Sciences, Oil & Gas and Technology.

EY-Parthenon was founded in 1991 as The Parthenon Group by William "Bill" Achtmeyer and John C. Rutherford, who at that time served as director at the management consultancy Bain & Company.

In the subsequent years the firm grew rapidly and merged with Big Four professional services company Ernst & Young in 2014.

[17] It announced its first innovation collaboration with the global start-up ecosystem Plug and Play in October 2020 to enable their clients to engage with disruptive digital technologies.