I need to cover our Safe Harbor statement, which can be found on Page 2 of our 1Q '12 earnings presentation, which says that the information on this call and in the presentation contain financial estimates and other forward-looking statements that are subject to risks and uncertainties. Actual results may vary from those statements. A discussion of factors that may affect future results is contained in Level 3's filings with the Securities and Exchange Commission. Finally, please note that on today's call and in the earnings presentation, we will be referring to certain non-GAAP financial measures. Reconciliations between the non-GAAP financial measures and the most comparable GAAP financial measures are available on the press release, which is posted on our website, at www.level3.com.
With that, I'll turn the call over to Jim.
James Q. Crowe
Thank you, Valerie. As is our normal practice in our prepared remarks this morning, our CFO, Sunit Patel, will discuss financial results for the quarter and the outlook for 2012. Our Chief Operating Officer, Jeff Storey, will discuss operational matters, including segment results, provide an update and status of integration, planning and implementation and some general remarks about the market and the industry. I'll provide some summary comments, then we'll open it up for questions and answers.Sunit? Sunit S. Patel Thank you, Jim, and good morning, everyone. I'll start with Slide 3 on the external earnings presentation with the summary of the quarter. Overall, Core Network Services revenue grew 1.2% sequentially on a constant-currency basis, strengthening from the 0.8% growth we saw in the fourth quarter. We continue to make progress on achieving synergies as we integrate the Global Crossing acquisition. Adjusted EBITDA grew nicely during the quarter. We also made significant progress this quarter in achieving capital expenditure synergies. Turning to the detailed results for the first quarter 2012 on Slide 4. We are pleased to see the 1.2% sequential Core Network Services revenue growth on a constant-currency basis, especially since the first quarter is genuinely a seasonally weaker quarter. This growth was primarily a result of strong gains from our enterprise customers in North America and Latin America. We saw growth from large enterprise and midmarket customers during the quarter.