Consulting Firms

American Institutes for Research, AIR A nonprofit consulting firm that applies social science principles to real world problems, including those of the workplace.
Development Dimensions International, DDI One of the largest I/O consulting firms in the world.
Expert Survey Systems, Inc. A consulting firm specializing in organizational (employee) surveys. Site has a lot of useful information about conducting surveys.
The Hay Group A large international management consulting firm.
Jackson Leadership Systems A consulting firm that specializes in leadership development, (executive coaching, leader selection)
The Kingwood Group A small I/O consulting firm that provides a wide range of services.

Performance Assessment Network, PAN

A company that carries a large number of varied I/O assessments ranging from selection tests to occupational stress surveys.
Personnel Decisions International, PDI One of the largest I/O consulting firms in the world.
Psychological Corporation One of the major psychological testing companies.
Talentkeepers Specializes in retaining good employees.
Wilson Learning Corporation International consulting firm that specializes in assessment and training.
RHR International Specializes in executive development.