This paper will review recent semiconductor laser research and development, including mode control, materials, degradation and application. It is concerned with understanding of the basic mechanism for laser performance, and its major emphasis is placed on the material and degradation problems. A new lattice matching technique utilizing the flexibility of the quaternary material has been developed for the (InGa)(AsP)/InP device for one micrometer wavelength range. Vapor phase epitaxial methods using metal organic sources or halide transports have been successful for (AlGa)As and (InGa)(AsP) systems respectively. Understanding on degradation mechanisms in (AlGa)As device has made progress, but further mechanism studies will be required, including those in other materials for visible and one micrometer ranges.