The useful electrooptic effects in lead lanthanum zirconate titanate (PLZT) ceramics divide into three general classes: variable birefringence, light scattering, and surface deformation. These effects are related to electrical switching of ferroelectric domains and electrically induced changes in the lattice distortion. Certain compositions exhibit memory properties due to remanent polarization of the domains, while some nonremanent compositions offer an electrostatic memory capability. A number of memory and display devices use longitudinal electrooptic effects. All three classes of electrooptic effects have been utilized in ferroelectric-photoconductor devices for information storage and display. Longitudinal light depolarization scattering is useful in alpha-numeric displays as is a fringe-field effect. The three classes of electrooptic effects in PLZT ceramics are also under evaluation for use as optical data input devices for optical memory systems.