Abstract: Recent theoretical and experimental results on coherent passive mode locking in lasers due to self-induced transparency are revised. In contrast to traditional laser systems, where passive mode locking occurs due to the effects of incoherent gain and absorption saturation, this regime of mode locking arises due to coherent interaction between light and matter. Theoretical results are presented that demonstrate the possibility of obtaining single-cycle pulses in a laser with a linear cavity of ultrashort length. Results are also presented from what are apparently the first experiments on coherent mode locking due to self-induced transparency in lasers.