This book constitutes the proceedings of the 23rd International Conference on Business Information Systems, BIS 2020, which was planned to take place in Colorado Springs, CO, USA. Due to the COVID-19 pandemic, the conference was held fully online during June 8–10, 2020. This year's theme was "Data Science and Security in Business Information Systems". The 30 contributions presented in this volume were carefully reviewed and selected from 86 submissions. The book also contains two contributions from BIS 2019. The papers were organized in the following topical sections: Data Security, Big Data and Data Science, Artificial Intelligence, ICT Project Management, Applications, Social Media, Smart Infrastructures.