An illustrative, device-systems-level desirability optimization analysis is performed for a number of important electro-optic materials that are candidates for use in high-speed guided-wave optical devices. Ferroelectric materials with high and low transition temperatures, cubic crystals, organic crystals, and alloy semiconductors are considered. The simple bulk (lumped-type) guided-wave phase modulator is taken as the initial screening device. Performance measures such as electrical power supply constraints and the device's maximum operating speed are analyzed as a function of system variables that include material properties and electrode architectures. A desirability analysis is presented as a composite mathematical function that describes two or more indepen-dent performance measures in terms of all relevant system variables. This function is displayed graphically to identify those sets of system variables that jointly optimize the performance measures of greatest interest. The initial screening analysis ignores propagation loss and less-than-ideal overlap between electrical and optical fields. Potassium niobate, barium titanate, and lithium niobate are found to be among the more desirable electro-optic materials. The use of dielectric buffer layers, several thousand angstroms thick, is found necessary to isolate the modulator electrodes from materials of high dielectric constant, high electro-optic strength such as potassium niobate. Buffer layers, however, are generally unnecessary when the lower permittivity and lower electro-optic strength materials such as lithium niobate are used.