After a year in which the revenues of the global public relations industry declined by more than 10 percent, it is worth remembering that at the end of the day, building a great PR agency is largely about doing great work. And over the past 12 months, no agency did more great work than Ketchum, which is why the Omnicom-owned firm is our Large Agency of the Year for 2009.

Omnicom has decided not to allow its various subsidiaries to reveal information about their billings, but the holding company saw its PR revenues decline by 15 percent in 2009, and there’s no reason to believe that Ketchum was immune to the forces that battered the global marketing and communications services business. But what is clear is that despite difficult economic circumstances, the firm continued to produce work of the highest caliber for a wide range of clients in a wide range of industries.

Ketchum’s work on behalf of Doritos—inviting consumers to “Crash the Super Bowl” with user-generated advertising—was recognized by this publication as the Campaign of the Decade and enjoyed its fourth year of success in 2010. The firm also took home the Campaign of the Year award at the PR Week awards for its work on behalf of Dreyer’s Ice Cream, and led the way among all agencies with 22 finalists for the North American SABRE Awards competition.

The highlights ranged from managing public relations for the 50th anniversary of Barbie, a campaign that revitalized the image of Mattel’s most iconic brand with a Barbie runway show at Mercedes-Benz Fashion Week to helping FedEx respond to the economic downturn with a much-imitated Free Resume Printing Day; from supporting (with several partner agencies) IBM’s vast Smarter Planet initiative to working with Walgreens to help consumers prepare for flu season.

Beyond all that great work, it wasn’t a bad year for new business either: Ketchum picked up assignments from clients such as Philips (as part of Omnicom’s One Voice agency team), Applied Materials, the Centers for Medicare & Medicaid Services, Newell Rubbermaid and more; added more multi-market, multi-discipline assignments to a roster that includes blue-chip brands such as FedEx, IBM, Kodak, Nestle and Nokia; and retained all of its top 50 clients.

Finally, the firm expanded its global footprint more significantly than any of its multinational peers via a merger with sister agency Pleon in Europe, a move that almost certainly elevated Ketchum into the top four firms in the world.