Revenues for the second quarter increased 16.1% over the second quarter of last year to $1 billion. For the second quarter, diluted earnings per share were $0.15 compared to diluted earnings per share of $0.16 in the second quarter of last year. Adjusted diluted earnings per share were $0.19 compared to adjusted diluted earnings per share of $0.22 in the same quarter last year. Both our 12-month and total backlog at the end of the second quarter were at record levels. Our 12-month backlog at the end of the second quarter increased 19.3%, and total backlog increased 18.2% compared to backlog at the end of the second quarter of 2010.
During the quarter, our Electric Power segment generated revenues of $667 million, and revenues grew organically by 32% compared to the same period last year. We continue to see momentum build in this segment, and expect revenue growth and margin expansion throughout this year as we continue to mobilize on large transmission projects. The increase in Electric Power segment revenues was partially offset by our Natural Gas and Pipeline segment, which experienced a 20% decrease in revenues to $210 million compared to the same period last year. The revenue decline was due to continued delays in large diameter transmission pipeline work primarily related to regulatory headwinds. However, since the end of the quarter, we have been awarded approximately $150 million of transmission pipeline work, most of which is expected to generate fourth quarter revenues. We expect this momentum to build with future awards throughout the remainder of this year and 2012.
While our Telecommunications segment revenues were 10% lower for this quarter versus the same period last year, we anticipate this segment's revenues will begin to accelerate during the third quarter and continue throughout this year, driven by broadband stimulus, 4G and LTE opportunities. Overall, we are seeing positive trends across all of our operating segments as we move into the third quarter despite continued regulatory and environmental delays on some projects.