The present volume contains the proceedings of the First International Workshop on Graphical Models for Security (GraMSec'14). The workshop was held in Grenoble, France, on April 12, 2014, as one of the satellite events of the European Joint Conferences on Theory and Practice of Software 2014 (ETAPS'14). Graphical security models provide an intuitive but systematic methodology to analyze security weaknesses of systems and to evaluate potential protection measures. Such models have been subject of academic research and they have also been widely accepted by the industrial sector, as a means to support and facilitate threat analysis and risk management processes. The objective of GraMSec is to contribute to the development of well-founded graphical security models, efficient algorithms for their analysis, as well as methodologies for their practical usage. The workshop brings together academic researchers and industry practitioners designing and employing visual models for security in order to provide a platform for discussion, knowledge exchange and collaborations.