The 4th International Congress on Environmental Modelling and Software aims to enhance environmental processes by means of fostering the discussion and interchange of challenges, solutions, ideas, new methods and techniques, and future research lines in environmental modelling & software. The congress joins together several interest groups working in different but complementary features and/or scientific fields in Environmental Modelling, Assessment, Decision Making and Information Technologies. This time, the focus will be stressed on Integrating Sciences and Information Technology for Environmental Assessment and Decision Making.