Darrin, thanks for the question. I'll start with the first quarter and then talk about what we're looking out for the full year. Obviously, what you saw, the first quarter was our highest-profitability metrics ever and a beat at the high end of our guidance of about $119 million from an adjusted OI perspective, with again, nearly doubling in terms of EBITDA on a year-over-year basis.
I think there's kind of three key things to point out. Obviously, there's continued strong growth and momentum across each of the two ecosystems, Square and Cash App, with 19% growth and 25% growth, respectively. But from an expense discipline perspective, three key things I'd call out.
First is our personnel cap, which is driving the right level of sharpening our strategy and prioritization and scoping our work, as Jack mentioned, and we remained under our 12,000-person cap at the end of the first quarter. Second, it's driving leverage across each of our areas of corporate overhead, whether it's T&E or professional fees, real estate, software and data fees. And third, it's around our structural costs and continuing to focus on ways that we can improve there. And do want to note, as we've called out in our shareholder letter, in the first quarter, we also benefited from $52 million in out-of-period items in Q1, mostly related to the releases of risk-loss provisions established in prior periods. So that's an important thing to note for the first quarter.
More broadly, when we look at the full year, from a profitability perspective, we've raised our profitability expectations both in EBITDA and adjusted OI basis not only for the full amount of outperformance relative to the high end of our guidance for Q1 but also an improved expectation for the remainder of the year where we expect to keep screws tight in terms of discipline and efficiency in how we run our business, but where we also see the flow-through of strong incremental margins in each of our businesses as we continue to grow Square and Cash App strongly for the remainder of the year, but also leaving room for us to invest in growth initiatives in the back half of the year. That should benefit our future growth, particularly around sales and marketing. So those are the different levers that we're looking at and why we think we can drive continued profitability through the remainder of the year.