The production of a W boson decaying to eν or μν in association with a W or Z boson decaying to two jets is studied using 4 . 6 fb −1 of proton-proton collision data at √s = 7 TeV recorded with the ATLAS detector at the LHC. The combined WW + WZ cross section is measured with a significance of 3.4 σ and is found to be 68±7 (stat . )±19 (syst . ) pb , in agreement with the Standard Model expectation of 61 . 1±2 . 2 pb. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.