The two parts of this volume feature seventeen and six extended conference abstracts corresponding to selected talks given by participants at "Joint CRM-Imperial College Workshop in Complex Systems" and "Emergence, Spread and Control of Infectious Diseases" respectively, both held at the Centre de Recerca Matematica in Barcelona in spring 2013. Most of them are short articles giving preliminary presentations of new results not yet published in regular research journals. The articles are the result from a direct collaboration among active researchers in the area after working in a dynamic and...