This book constitutes the refereed proceedings of the First International Conference on Systems Modelling and Management, ICSMM 2020, planned to be held in Bergen, Norway, in June 2020. Due to the COVID-19 pandemic the conference did not take place physically or virtually. The 10 full papers and 3 short papers were thoroughly reviewed and selected from 19 qualified submissions. The papers are organized according to the following topical sections: verification and validation; applications; methods, techniques and tools.