A study of W <sup>±</sup> Z production in proton-proton collisions at √s = 7 TeV is presented using data corresponding to an integrated luminosity of 4.6 fb<sup>−1</sup> collected with the ATLAS detector at the Large Hadron Collider in 2011. In total, 317 candidates, with a background expectation of 68 ± 10 events, are observed in double-leptonic decay final states with electrons, muons and missing transverse momentum. The total cross-section is determined to be be σ<sup>tot</sup> <inf>WZ</inf> = 19.0<sup>+1.4</sup> <inf>−1.3</inf> (stat.) ± 0.9(syst.) ± 0.4(lumi.) pb, consistent with the Standard Model expectation of 17.6<sup>+1.1</sup> <inf>−1.0</inf> pb. Limits on anomalous triple gauge boson couplings are derived using the transverse momentum spectrum of Z bosons in the selected events. The cross-section is also presented as a function of Z boson transverse momentum and diboson invariant mass.