A new initiative, GEM (Global earthquake Model), is under way to estimate earthquake risk and potential losses worldwide. General challenges the community of seismologists and engineers face include the following issues: Architecture of the computer codes to calculate risk and losses, databases such as population distribution as a function of space and time, distribution of building types as a function of region and size of settlement, regional vulnerability functions, regional casualty matrices and regional attenuation functions. Specific local problems include distribution of population, building type, soil conditions, schools, hospitals and critical facilities within and surrounding a city. With loss estimates in real-time as well as scenario mode the problem of accuracy of input parameters is of great importance. In order to advance the quality of risk and loss assessments, we invite contributions regarding any of the aforementioned topics.