Towers Perrin
203-326-5400, www.towersperrin.com
Sets executive pay levels for major corporations such as Boeing and 3M; rates are between $500 and $1,000 per hour.

Mercer Human Resource Consulting
312-902-7500, www.mercer.com
Focuses on the pharmaceutical, insurance, and media sectors (though it serves other clients as well). Mercer also sells research on C.E.O. pay trends. In addition to determining executive pay, Mercer will rate the charter and operations of clients’ comp committees.

Frederic W. Cook & Co.
212-986-6330, www.fwcook.com
Referred to as the "dean of executive compensation consultants" because it focuses exclusively on that factor, the firm has pioneered some pay practices. Clients include American Express, Procter & Gamble, General Electric, Mattel, and 3M.

Hewitt Associates
847-295-5000; 219-838-8643, www.hewittassociates.com
Known for excellent survey data in the retail sector. Consultants are described as “Midwestern”; clients include Dow Chemical and Phillip Morris.

Watson Wyatt Worldwide
212-725-7550, www.watsonwyatt.com
Offers good survey data for executives at smaller companies, as well as actuarial services, health and welfare specialists, and “communicators” who explain comp packages to clients such as Wal-Mart, General Mills, and Schering-Plough.

Hay Group
215-861-2000, www.haygroup.com
A leader in international pay practices. The Philadelphia-based company closely tracks compensation for executives and board members in the U.S., Europe, and elsewhere. Clients include Morgan Stanley, Office Depot, and Mattel.

ExeQuity
847-996-3960, www.exqty.com
New firm founded by former pay consultants from Hewitt. Offers a small portfolio of services concentrating on exec pay consulting. Counts clients such as Verizon and the New York Times Co.