The management of cholangiocarcinoma remains a major challenge. With the establishment of modern surgical, interventional and systemic treatment options over the last few years, the treatment of cholangiocarcinoma more than ever requires an interdisciplinary approach and open dialogue. Therefore, the 3rd International Expert Meeting in Mainz will bring together renowned specialists in the field of surgery, medical oncology, pathology, endoscopy, diagnostic and interventional radiology as well as radiotherapy. Experts from all around the world will meet in Mainz for an intensive two-day discussion on diverse aspects of cholangiocarcinoma. The program 2020 comprises most relevant topics and critical issues on the diagnosis and management of intrahepatic, perihilar as well as distal cholangiocarcinoma: as observed in other cancer types, molecular profiling has started to gain increasing relevance in the treatment of advanced cholangiocarcinoma. Moreover, novel diagnostic approaches as well as tools for local therapy have been developed, which require particular attention. Furthermore, controversies on the optimal preoperative work-up including biliary drainage as well as potential indications for neoadjuvant and adjuvant targeted therapy will be major topics. Also, IgG4-associated cholangitis and Klatskin-mimicking lesions that are still highly difficult differential diagnoses and pose major therapeutical problems will be highlighted. Finally, operative techniques, pitfalls in surgery and surgical strategies are presented focusing on vascular resection, the laparoscopic and robotic approach as well as ALPPS.