CR-39 plastic sheets have been tested for their response to protons, deuterons, and alpha particles. The enlargement of the latent damage trail has been studied (a) under varying experimental conditions, and (b) as a function of energy, restricted energy loss, and Z2crr/β2of the light charged particles. The critical angles of etching of CR-39 and its response curves have been obtained. Scanning-Electron-Microscopy (SEM) has been employed for studying the profiles of the etched channels.