The 20th National Laser Symposium (NLS-20) was organized at Crystal Growth Centre, Anna University, Chennai, during January 9 – 12, 2012. The symposium was sponsored by the Board of Research in Nuclear Sciences (BRNS) of Department of Atomic Energy organized and was organized in collaboration with Indian Laser Association (ILA).  It was inaugurated by Bharat Ratna Dr. A. P. J. Abdul Kalam, former president of India and an eminent scientist, followed by keynote address by renowned scientist Prof. Chandrasekhar Joshi of UCLA, USA. The symposium covered recent developments in the fields of physics, technology, and applications of lasers. Apart from invited talks by leading experts, there was poster presentation of contributed papers, and Ph.D. theses presentations by students.  21 invited talks were delivered by leading experts in the field both from India as well as abroad whereas around 270 research papers were presented by the researchers from different parts of the country. 10 Ph. D. theses related to the works on lasers and their applications were also presented. Prior to the symposium, ILA organized short tutorial courses related to the field. Many vendors from India and abroad also displayed their products, services related to the lasers and their applications