We review progress in novel semiconductor lasers positioned to enable planar optoelectronic integration and to facilitate the realization of functional photonic devices. Lateral injection of current into the active region of a semiconductor laser has been pursued, mostly empirically, since the early 1970s. In this work, we focus on recent advances in the development of a device model which accounts for the qualitative structural and operational differences between lateral and conventional vertical injection lasers. We review fabrication methods -both established and emerging - suitable for LCI laser realization. Finally, we report the results of recent combined theoretical-experimental explorations of laser performance.