This book constitutes the refereed proceedings of the 15th European Conference on Symbolic and Quantitative Approaches to Reasoning with Uncertainty, ECSQARU 2019, held in Belgrade, Serbia, in September 2019.The 41 full papers presented together with 3 abstracts of invited talks inn this volume were carefully reviewed and selected from 62 submissions. The papers are organized in topical sections named: Argumentation; Belief Functions; Conditional, Default and Analogical Reasoning; Learning and Decision Making; Precise and Imprecise Probabilities; and Uncertain Reasoning for Applications.