This book constitutes the thoroughly refereedpost-conference proceedings of the 12th International Conference on ArtificialEvolution, EA 2015, held in Lyon, France, in October 2015.The 18 revised papers were carefully reviewed andselected from 31 submissions. The focus of the conference is on followingtopics: Evolutionary Computation, Evolutionary Optimization, Co-evolution,Artificial Life, Population Dynamics, Theory, Algorithmics and Modeling,Implementations, Application of Evolutionary Paradigms to the Real World,Dynamic Optimization, Machine Learning and hybridization with other softcomputing techniques.