This book contains the refereed proceedings of the 18th International Conference on Business Information Systems, BIS 2015, held in Poznan, Poland, in June 2015. The BIS conference series follows trends in academic and business research; thus, the theme of the BIS 2015 conference was "Making Big Data Smarter." Big Data is now a fairly mature concept, recognized and widely used by both research and industry. Together, they work on developing more adequate and efficient tools for data processing and analysing, thus turning "Big Data" into "Smart Data". The 26 revised full papers were carefully reviewed and selected from 50 submissions. In addition, two invited papers are included in this book. They are grouped into sections on big and smart data, semantic technologies, content retrieval and filtering, business process management and mining, collaboration, enterprise architecture and business-IT-alignment, specific BIS applications, and open data for BIS.