Good morning, and thank you for joining us to discuss our results as reported earlier today. I'm Brian Duperreault, President and CEO of Marsh & McLennan Companies. Joining me on the call today is Dan Glaser, Group President and CEO; and Vanessa Wittman, our CFO. Also, I'd like to welcome our Operating Company CEOs, Peter Zaffino of Marsh; Alex Moczarski of Guy Carpenter; Julio Portalatin of Mercer; and John Drzik of Oliver Wyman. Also with us is Mike Bischoff.
My remarks will focus primarily on our full-year results and Dan will provide more detail on the fourth quarter. Vanessa will then update you on our financial position. Before we begin the discussion of our results, I'd like to welcome Julio to our company. Julio joined us as President and CEO of Mercer 2 weeks ago. He comes to us from AIG, where he held a broad range of senior positions over 19 years. Most recently, he was President and CEO of Chartis Growth Economies. Julio has had a very successful track record of running large global businesses. His strong leadership characteristics and international experience will serve him well as Mercer’s CEO.
Now let's move to our financial results. I'm very pleased that we continue to deliver revenue and earnings growth across the enterprise. Marsh & McLennan's performance this year was outstanding. In 2011, we generated revenue growth of 9% with 5% growth on an underlying basis. Importantly, we continue to achieve this revenue growth while maintaining control over expenses with adjusted underlying expenses increasing 4%. As a result, we produce a 12% growth in adjusted operating income for the year. In fact, this is the second consecutive year that both of our operating segments achieved double-digit growth in operating income.You've heard me talk many times since our September 2010 Investor Day about our plans to produce double-digit organic growth in adjusted operating income. Over the past 2 years, we have delivered against that goal, averaging 11% growth. Within Risk and Insurance Services, revenue increased 9%. Importantly, underlying revenue growth of 5% represents a significant increase from the 2% underlying growth in the prior year, and we generated 12% growth in adjusted operating income and margin improvement.