Before we begin the commentary, I would like to remind you that statements made during today's conference call and webcast, which are not historical facts, might be considered forward-looking statements. Such statements may include comments regarding future financial results and are subject to a number of risks and uncertainties, certain of which are beyond Covance's control. Actual results could differ materially from such statements due to a variety of facts, including the ones outlined in our SEC filings. Certain of the 2011 financial measures we will discuss on this call are non-GAAP measures, which exclude the effects of events outside of our normal operations, such as items associated with our previous restructuring. We believe that providing these measures helps investors gain a more complete understanding of our results and is consistent with how management views our financial results. For a reconciliation of GAAP to pro forma results, please refer to supplemental schedules included in our press release issued last night.
Now I will turn it over to Bill for a review of our financial performance, which begins on Page 4 of the slide show.
William E. Klitgaard
Thank you, Paul. Good morning, everyone. All results in the first quarter of 2012 are presented on a GAAP basis, and in my comments, I'll be comparing those results to previously reported pro forma results from 2011. Net revenues for the first quarter were $531 million, that's an increase of 5.7% over the first quarter of last year. Growth was 5.9% on a constant dollar basis. Sequentially, a stronger U.S. dollar resulted in a slight $2.4 million FX headwind.Operating income in the first quarter was $46.1 million, resulting in an operating margin of 8.7% of net revenue. This was down 220 basis points sequentially and 80 points year-on-year. EPS was $0.60 per share, which is flat year-on-year and down $0.13 from last quarter. The sequential decline in earnings per share was driven by weak performance in Early Development and to a lesser extent, increased spending on information technology, which were partially offset by the strong performance in Late-Stage.