Wide bandgap II-VI materials and structures based on ZnCdMgSe alloys lattice matched to InP substrates have been investigated. Quantum well (QW) structures designed to emit throughout the entire visible spectral range M cre constructed by varying the QW layer thickness and/or composition. Light emitting diode (LED) structures were grown, fabricated and tested. Electroluminescence emission in the blue, green, yellow and red regions of the visible spectral range were obtained from lattice-matched or pseudomorphic structures that varied only in the composition or thickness of the QW layer. Lattice-matched distributed Bragg reflector (DBR) structures with reflectivity maxima. in the red, green and blue were also grown and characterized. Since the LED and DBR structures are made from the same materials it should be possible to combine these into a single structure for the design of high performance LEDs and vertical cavity surface emitting lasers that operate in the entire visible range.