The first ZnSe-ZnCdSe double-heterostructure light-emitting diodes (LEDs) and photopumped laser structures on ZnSe substrates have been successfully grown by molecular beam epitaxy. The LEDs emit bright blue/green electroluminescence at room temperature, with the emission peak centered at 492 nm. Photopumped laser emission was also observed from ZnSe-ZnCdSe multiple-quantum-well structures grown on ZnSe substrates. The cleaved-cavity devices display stimulated emission in the deep-blue spectral region near 477 nm at 10 K and at 478.8 nm at 80 K.