This book constitutes the proceedings of the 11th European Workshop on Performance Engineering, EPEW 2014, held in Florence, Italy, in September 2014. The 18 full papers presented in this volume were carefully reviewed and selected from 30 submissions. The papers are organized in topical sections named: cloud performance modelling; queueing and fluid models; performance of computation and programming; fitting; urban traffic modelling; decision making; and Markovian models, above and beyond.