We report the growth on polycrystalline yttria‐stabilized zirconia substrates of YBa2Cu3O7−xfilms withJc(77 K)=11 000 A/cm2andJc(4.2 K)=122 000 A/cm2by pulsed laser ablation. TheseJcvalues are among the highest reported for YBa2Cu3O7−xon any polycrystalline substrate and approach the intrinsic upper limit for films with large‐angle grain boundaries, as indicated by recent bicrystal experiments. We find that the substrate temperature during film growth is most important in obtaining highJcpolycrystalline films. Although the magnetic field dependence ofJcindicates the presence of weak links, the behavior ofJc(4.2 K,H) suggests that a percolative path consisting of low‐angle grain boundaries exists in the films, resulting inJc(4.2 K, 60 kOe)=4100 A/cm2.