Electric field forced antiferroelectric to ferroelectric phase switching has been demonstrated in thin films of Pb0.97La0.02(Zr,Ti,Sn)O3 perovskites for the first time. Several compositions in the tetragonal antiferroelectric phase field of this system were prepared in thin film form by a sol‐gel technique. Forward and reverse switching threshold fields of 27–103 kV/cm and 18–62 kV/cm, respectively, were determined from polarization‐electric field hysteresis and incremental capacitance data. Switching times as fast as 300 ns were recorded for one of the antiferroelectric compositions. An electric field induced longitudinal strain of 0.16% was measured for a film of composition (Pb0.97La0.02)(Zr0.60Ti0.10Sn0.30)O3 using a laser ultradilatometer. These films are candidate materials for high charge storage integrated capacitors and microelectromechanical devices requiring large nonlinear strain response.