During and after World War II, Hewitt's expertise became valuable when the government instituted "pay-as-you-go" income taxes in 1943 and the U.S. cost of living increased more than 25 percent in 1945.

Hewitt began offering its clients statements to track their employee benefits and had pioneered the use of financial goals for company investments.

Despite the furore, the new office opened in Orlando in 1997, during a fiscal year (ending in September) in which Hewitt's revenues reached close to $700 million.

Such advancements, along with being the first HR industry firm to launch a corporate web site, landed Hewitt among PC Week's Top Ten Most Technologically Innovative Companies.

Hewitt also continued its surveys, developing the Health Value Initiative in 1999 to measure the effectiveness and quality of more than 2,000 healthcare programs worldwide.

The company also announced the merger of its British and Irish operations with the United Kingdom's Bacon & Woodrow, a retirement and HR management consulting firm.

Hewitt briefly offered Sageo, an online service where participants could compare, choose, and enroll in benefit programs.

Hewitt put its new funds to work, paying off debt, purchasing France's Finance Arbitage, an investment consultancy firm, and spearheading expansion plans for the United Kingdom and China.

In 2003 Hewitt took over the Cork, Ireland-based Becketts, a benefits consultancy, and bought the software programs and payroll services of Cyborg Worldwide Inc.

These moves, along with several others, prompted the Chicago-based Crain's Chicago Business to name Hewitt one of the area's fastest growing public firms, with fiscal revenues topping $1.9 billion for the year.

On July 12, 2010, Chicago-based insurance broker, Aon Corp., announced that it had agreed to buy Hewitt Associates for $4.9 billion in cash and stock.

[1] In March 2020, Aon had agreed to buy Willis Towers Watson months after the breakdown of negotiations between the two professional services firms.

In June 2003, Hewitt announced the completion of the acquisition of Northern Trust Retirement Consulting, L.L.C., expanding its portfolio of outsourcing clients.

On October 1, 2004, Hewitt completed the acquisition of Irvine, California-based Exult Inc., a company specializing in Human Resources Business Process Outsourcing or HR BPO.

This move was to ensure Hewitt would remain competitive within the HR consulting and outsourcing space, in which HRBPO was a rapidly growing area.

The announcement was made in the face of Hewitt's declining stock performance and market worries about the entire BPO sector, but Gifford, who has served as chief executive officer since 1992, indicated the decision was his own, and that he planned to retire.

Just after the closing of the stock market on Thursday, August 10, 2006, the company announced the appointment of the fourth CEO of Hewitt Associates, Russell P. Fradin, whose tenure commenced on September 5, 2006.

[11] Ari Jacobs, the firm's Senior Partner of Global Retirement Solutions Leader, was named 2012's number 1 Knowledge Broker by aiCIO magazine.