Ultrafast Magnetism I : Proceedings of the International Conference UMC 2013 Strasbourg France October 28th November 1st 2013 This volume on Ultrafast Magnetism is a collection of articles presented at the international “Ultrafast Magnetization Conference” held at the Congress Center in Strasbourg France from October 28th to November 1st 2013. This first conference which is intended to be held every two years received a wonderful attendance and gathered scientists from 27 countries in the field of Femtomagnetism encompassing many theoretical and experimental research subjects related to the spins dynamics in bulk or nanostructured materials. The participants appreciated this unique opportunity for discussing new ideas and debating on various physical interpretations of the reported phenomena. The format of a single session with many oral contributions as well as extensive time for poster presentations allowed researchers to have a detailed overview of the field. Importantly one could sense that in addition to studying fundamental magnetic phenomena ultrafast magnetism has entered in a phase where applied physics and engineering are playing an important role. Several devices are being proposed with exciting R&D perspectives in the near future in particular for magnetic recording time resolved magnetic imaging and spin polarized transport therefore establishing connections between various aspects of modern magnetism. Simultaneously the diversity of techniques and experimental configurations has flourished during the past years employing in particular Xrays visible infra red and terahertz radiations. It was also obvious that an important effort is being made for tracking the dynamics of spins and magnetic domains at the nanometer scale opening the pathway to exciting future developments. The concerted efforts between theoretical and experimental approaches for explaining the dynamical behaviors of angular momentum and energy levels on different classes of magnetic materials are worth pointing out. Finally it was unanimously recognized that the quality of the scientific oral and poster presentations contributed to bring the conference to a very high international standard