ZnS and ZnSe are important materials for laser windows and optical thinfilm coatings. Understanding the laser-induced damage mechanism in optical materials provides the ability to make improved damage-resistant materials. Photoconductivity (PC) techniques have demonstrated the capability to provide information on carrier production that can lead to electron avalanche by single or multiple photon absorption processes produced by a high-intensity laser beam. A study of the linear PC using a monochromated Xe lamp and the nonlinear PC using various lasers as excitation sources will be presented for chemically vapor-deposited ZnS and ZnSe.