On behalf of the Steering Committee of the Complex Systems Society, the Organizing Committee of CCS2018 and the Aristotle University of Thessaloniki, I would like to invite you to CCS2018, to be organized in Thessaloniki, Greece in the period September 23-28, 2018. This Conference is in line with the series of meetings previously held in Cancun, Mexico(2017), Amsterdam, Netherlands(2016), Tempe, Arizona,USA(2015), Lucca, Italy(2014), and more meetings in previous years. All these past meetings have delivered the highest quality of presentations, the most up-to-date findings, have been attended by the pioneers in the field of Complex Systems, as well by young aspiring students, numbering an attendance of close to one thousand. Our purpose is to deliver a well-tailored and focused event of the highest scientific and organizational standards in the vibrant and friendly city of Thessaloniki, which is renown for its beauty, its warm hospitality and history of Greek, Roman, Ottoman and Jewish ancestries, spanning a period of over 2300 years.