Ferroelastic toughening in Pb(Zr1-xTix)O3 (PZT) ceramics can be augmented by phase transformation toughening through the inclusion of partially stabilized TZ (PZTZrO2). In order to deconvolve both these toughening modes, cubic Pb1-yLay(Zr1-xTix)O3 (PLZT) with and without zirconia (PLZTZrO2) was characterized. R curve and stressstrain behavior yielded a quantification of strong toughening and a lack for switching propensity that could be contrasted to PZT and zirconia-toughened PZT. A clear path for toughening of PZT for future application is therefore provided.