Manpower Inc. (NYSE: MAN) today was named to the Ethisphere Institute's 2011 world's most ethical companies list. Manpower was the only firm listed in the staffing category.

Fluor Corp., which has a staffing firm subsidiary, was listed in the engineering and design category.

Ethisphere is an international think-tank dedicated to creating, advancing and sharing best practices in business ethics, corporate social responsibility, anti-corruption and sustainability. The group evaluated nominated companies' ethics quotient process through queries on corporate governance, risk, sustainability, compliance and ethics.

For more on the list, click here.