These proceedings contain the papers presented as oral and poster presentations at the 44d Annual Symposium on Optical Materials for High-Power Lasers. The conference was held at the National Institute of Standards and Technology facility in Boulder Colorado on 23-26 September 2012. The symposium was divided into the traditional sessions devoted to the following major topics: thin films; surfaces, mirrors and contamination; fundamental mechanisms; materials and measurements. A mini-symposium devoted to laser-induced plasma interactions was held this year. The starting event of the symposium was a round-table discussion on mechanisms of surface and bulk laser damage held by Stavros Demos and Michael Feit (both with Lawrence Livermore National Laboratory) on Sunday evening. The conference was opened by Dr. Joseph A. Menapace with a symposium welcome. Dr. Gregory J. Exarhos of Pacific Northwest National Laboratory (USA), Dr. Vitaly Gruzdev of the University of Missouri, Columbia (USA), Dr. Joseph A. Menapace of the Lawrence Livermore National Laboratory (USA), Dr. Detlev Ristau of the Laser Zentrum Hannover e.V. (Germany), and Dr. M J Soileau, of the University of Central Florida (USA) co-chaired the symposium. The founding organizers are Dr. Arthur H. Guenther and Dr. Alexander J. Glass. Eighty-two papers were accepted for presentation at this meeting (same as in 2011), and 75 of them were presented (improvement by seven papers as compared to 2011), including oral and poster presentations plus the mini-symposium. No parallel sessions were held allowing the opportunity to discuss common research interests with all the presenters. With 157 participants attended the meeting (about 5% improvement as compared to 2011), it offered an opportunity to make many new acquaintances. Although held annually in the US, this is a truly International conference with 68 percent of the presentations coming from abroad. As usual, the National Institute of Standards and Technology in Boulder, Colorado, offered a setting conductive to interchanges between individuals working in closely related and complementary fields. We look forward to future opportunities to come together again in this setting. The 45th Annual Symposium of this series will be held in Boulder, Colorado, 22-25 September 2013. A continuous effort will be made to ensure a close liaison between the high-peak-power and high-average-power laser communities, as well as to include damage issues related to various research efforts and commercial laser applications. Two mini-symposia related to the subject of high-power fiber lasers and laser-damage applications are anticipated. Invited talks are also anticipated to open the four major topical areas and the mini-symposia. The principal topics to be considered as contributed papers in 2013 do not differ drastically from those enumerated above. We expect to hear more about the laser-damage issues for high-power ultrafast lasers, impacts of defects of optical components on the laser resistance and impacts of material composition/processing techniques since both of these topics continue to generate significant interest. High-energy laser windows, crystals, and transparent ceramics continue to place limitations on laser systems and so remain an active area of research and spirited debate. Refinement of the mitigation strategy consisting of damage initiation followed by arresting damage growth through post-processing techniques while not creating downstream damage is also expected to be a continued focus as a large number of laserresistant UV optics are manufactured for large-aperture fusion lasers. Short pulse laser optics and damage phenomena remain an active area of research. Recently increased activity in the field of ultra-short-pulse (femtosecond) laser-material interactions is expected to be one of growing topics of the future symposium. We also expect to hear more about new measurement techniques to improve our understanding of the different damage mechanisms or to improve the manufacturing of optical materials and thin films for optical components of greater laser damage resistance. Fundamental aspects of laser-induced damage including multiphoton and avalanche ionization, scaling of damage threshold with laser and material parameters continue to attract much attention. As was initially established in 1992, several distinguished invited speakers will make presentations of a tutorial or review nature, in addition, other contributors will cover late-breaking developments of interest to the attendees. The purpose of this series of symposia is to exchange information about optical materials for high-power/high-energy lasers. The editors welcome comments and criticism from all interested readers relevant to this purpose.