Thanks, Andrew. With our detailed results available in this afternoon's press release, I'm going to provide a short summary of our performance and then provide some additional color on the key levers in our business. I'll also provide our outlook for the second quarter.
Some of my comments here will be on a non-GAAP basis. Note that reconciliations of GAAP to non-GAAP metrics can be found in this afternoon's press release as well as in our 10-Q, both of which can be found on our website.
Overall, we had a strong quarter. Here are some of the highlights on a year-over-year basis. Gross billings, or the total amount spent by customers on Groupons, were $1.35 billion, up 103%, or 108% excluding changes in foreign exchange or FX. Revenues grew 89%, or 95% excluding FX. North American revenues grew 75%, and international grew 102%, or 112% excluding FX.
Our Q1 GAAP operating income on a consolidated basis was $39.6 million, which included $28 million in noncash stock-based compensation. Excluding these noncash charges, operating income would have been $67.6 million compared to a loss of $98.3 million in the first quarter of 2011 and an income of $18 million last quarter. FX changes did not have a material impact on profitability in the quarter.
North American segment operating income margin reached 16.8% and continued to make progress towards our long-term target of 25% to 30%. International segment operating income margin became positive at 8.5%. International operating margin continued to lag North America's due to our continued aggressive investment in early-stage markets.
Non-GAAP EPS for the quarter was $0.02 compared with a loss of $0.41 in the first quarter of 2011. GAAP EPS was negative $0.02 compared with a loss of $0.48 in the first quarter of 2011. This loss includes $28 million of stock-based compensation and $34.6 million of tax expense, or $0.10 per share in total on both a GAAP and a non-GAAP basis.
And finally, operating cash flow increased 367% to $83.7 million. Free cash flow in Q1 was $70.6 million, growing our trailing 12-month free cash flow to $310 million as of March 31, 2012. I'll talk more about Q1 free cash flow composition shortly.
Consistent with last quarter, we are profitable in many countries and subject to tax. For the time being, we remain unable to offset tax charges from profitable countries with NOL from unprofitable countries. Primarily as a result of these tax charges in our International headquarters initiative, our effective tax rate for the quarter remains well above our current average statutory rate of approximately 33%. We do expect our effective tax rate to decline over time.
Q1 EPS also includes a reduction of approximately $0.01 on both GAAP and a non-GAAP basis related to a $7.2 million reduction of earnings available to common shareholders as a result of our decision to purchase the remaining minority interest in certain consolidated subsidiaries. Going forward, we may elect to purchase additional minority interests related to other acquisitions.
Now I'll touch on our accounting revision filed March 30, which was primarily related to an increase in our refund reserve as of December 31, 2011. Customer refund activity in the first quarter of 2012 was consistent with the assumptions we made. We have not seen material changes in our overall category mix, price point or customer refund behavior.
Also, as it pertains to the material weakness designation that arose in connection with our year-end audit, we are implementing a comprehensive remediation plan that includes the hiring of additional staff at all levels in our finance department. We are also in the process of implementing the controls necessary to ensure that our internal controls over financial reporting are effective. As required by SOX, we will evaluate and report on the effectiveness of our internal controls at year end, and our evaluation will be reviewed by auditors as part of the 2012 year-end audit.
Now I'll move on to a review of some of the key operating fundamentals from the quarter. I'll frame my review of the financial fundamentals from Q1 in these 3 sections: First, revenue leverage, where the interplay between customer growth and revenue per customer expansion are 2 key levers for driving growth; Second, operating leverage, or the yield we realize on our core operating expenses. Our primary leverage point is our largest bucket of variable expense, marketing. In Q1, consistent with our execution over the past 12 months, we saw significant operating leverage from improved marketing efficiencies.
And third, strong free cash flow generation and the leverage we get from our balance sheet. Our business model possesses the benefits of a negative operating cycle that are not unusual in online retail and what's continued to drive healthy cash flow dynamics that further strengthen our balance sheet.
Let's start with revenue leverage. Our growth is primarily driven by 2 factors: new customers and how much these customers spend. Our growth in the quarter reflects our success in both of these areas. Our active customer count grew 36.9 million in the quarter, an increase of 140% year-over-year. Spend per customer was consistent with Q4, with both Groupons per customer and average price per Groupon holding about steady quarter-over-quarter on a worldwide basis.
Another way to look at customer spend behavior is to look at trailing 12-month gross billings per average active customer, which was $179 in the first quarter compared to $169 a year ago and $187 last quarter. North American Groupons per customer and average price point per Groupon both increased slightly, along with the growth in customers, to result in strong, sequential revenue growth we recorded in Q1. While Groupons per customer and price per Groupon both declined marginally in our International segment during Q1, this is in line with the opportunity Andrew highlighted earlier for us to evolve our technology platform and deploy improved personalization overseas.
We also benefited from improvements in our deals inventory and quality. Deal selection continued to expand as we secured more and more merchant partners located with closer proximity and in more dense concentration around our current and potential customer base. We surpassed 100,000 unique merchants featured for the first time in Q1, and our sales and sales support organization of over 5,000 people worldwide continues to form new merchant relationships that expand our reach on a daily basis. Getting more merchants in all markets and increasing deal relevance will be a key focal area for us as we continue to look at the ways to address the importance of proximity in our customers' decision-making progress.
In our local deals business, proximity is the #1 driver of purchase behavior. Our data suggests that deals that are within 5 miles of the user have more than a 5x conversion rate compared to deals that are more than 20 miles away. As Andrew mentioned, we've begun to roll out features like SmartDeals that not only provide a considerable improvement to the customer experience through relevance, but also give densely-populated markets like Chicago a 50% lift through some emails. SmartDeals is a key piece of the equation, but you'll also see us driving deeper into the surrounding areas of major metropolitan areas.
We're pleased to see the core local deals business continue to grow, but we're also happy with the progress of our new channels. Our results within our Getaways business in Q1 is a great example. Getaways continued to grow last quarter with a 45% sequential increase in the number of deals offered in the period to more than 540 deals. 30% of our Getaways purchases in North America in Q1 were from first-time Groupon customers. These are customers we might not have gained access to had it not been for our expansion into Getaways, and we now have the opportunity to sell them products and services from across our entire suite.
We also saw strong acceleration coming out of the fourth quarter in our North American Goods business. Our continued expansion into these new channels should further increase wallet share.
The second point I'll highlight from Q1 is our continued demonstration of operating leverage. Our largest variable expense bucket, marketing, is also our expense line of greatest leverage in the near to midterm. In Q1, about $39 million of the operating income improvement quarter-over-quarter was related to our increased efficiency of customer acquisition efforts. Marketing expense as a percent of revenue decreased from 78% in Q1 of last year to 32% in Q4 and further to 21% this quarter despite roughly the same number of paid and organic customer additions in each quarter. In Q1, repeat purchasers also grew more than 50% faster than first-time purchasers. These improvements came while lapping the highest trade and marketing spend in the company's history, which included large onetime deal promotions and broad-based marketing that ultimately came with lower-value customers. As a result, net active customer additions declined versus Q4 as we attrited some of those customers acquired in Q1 '11. At the same time, we added approximately the same number of new customers in Q1 as we did last quarter on 25% lower marketing spend.
Our Q1 marketing performance reflects continued execution against our plan to move from subscriber acquisition marketing to customer activation. We do not believe that this reduced level of spend is reflective of our normalized run rate. As we proceed, we believe that our long-term target marketing expense at 20% of revenue is still appropriate.
Finally, the third point I'll highlight is our strong cash flow generation and the leverage we get from our balance sheet. The powerful free cash flow dynamics of our business afford us great flexibility to invest in key talent and initiatives. At the end of March, we had $1.2 billion in cash and no long-term debt. Free cash flow, a non-GAAP measure, was $71 million for the quarter and $310 million in the trailing 12 months.
In Q1, we realized contribution to free cash flow from earnings and from the working capital benefit related to the natural spread between our receivables and merchant payables. This quarter, the timing of other AP and AR accounts, along with cash tax payments, led to a lower overall benefit from working capital accounts than we've seen in prior quarters. Cash taxes alone, all of which related to 2011, reduced free cash flow by approximately $35 million in Q1. We do expect additional cash tax payments while we complete the implementation of our International headquarters.
In summary, we're pleased with our financial performance in the first quarter, and we feel very good about the progress we're making with our key initiatives.
Turning now to our outlook for the second quarter. As always, our results are inherently unpredictable and may be materially affected by many factors, including a high level of uncertainty surrounding the global economy and consumer spending as well as exchange rate fluctuation. It is not possible to accurately predict demand, and, therefore, actual results could differ materially from our guidance. Our outlook further assumes that we do not make any acquisitions or investments and assumes no material changes in foreign exchange rates.
For Q2 2012, we expect revenue of between $550 million and $590 million or between 40% and 50% year-over-year growth. We expect second quarter GAAP operating income of between $25 million and $45 million as compared to an operating loss of $101 million in the second quarter of 2011. This outlook includes approximately $35 million in stock-based compensation. We do not anticipate any significant acquisition-related expenses in the second quarter.
This guidance reflects Andrew's commentary on our commitment to rolling out technology and process improvements internationally in a deliberate manner. The opportunity in front of us is significant, and we have built a foundation that continues to prove difficult for our competitors to match. We intend to continue to deepen the competitive moats around our business and to continue building for the long term, even though that may mean that we invest aggressively into our operational improvement initiatives in the short run so that we are well positioned for continued growth.
With that, I'm going to turn it back to Andrew for some closing comments.