“Developments and new challenges”, the overarching theme chosen for this 4th edition of the World Congress on Emulsions, was broken down into four proposals so as to provide focus for the call for papers which resulted in the receipt of 350 abstracts. The overwhelming and wide-ranging response to this call for papers has given shape to topics for 15 workshops, during which researchers from businesses, universities and public research institutes discussed the results of their work on the behaviour of systems, products or processes involving emulsions. Theme 1 : End use properties The formulation of an emulsion is conditioned by the properties sought for the emulsion borne product and the expected effect for the environment on or in which it is used. 4 topics were studied. One workshop was devoted to the theme of emulsions as a vector of a given property. The second workshop focused on the control of breaking behaviour, whether this phenomenon be intentional or is to be avoided. Two further workshops looked more specifically at the use of bitumen emulsions. One of these focused on the properties of the emulsion itself and the other on the properties of the emulsion-based product. Workshops: Drug Delivery, Biodisponibilité, Extraction Breaking Behaviour Formulation of emulsion based products End Use Properties of Bitume Emulsion Based Road Products Theme 2 : Product design. Conception. Preparation Before being able to use a product it has to be formulated and prepared. The 5 workshops organised under this title focused on some of the following themes: formulation methods; emulsion (bubble and solid mixes); description and mastery of interfacial properties; nanoemulsions, encapsulation. Workshops: Interfacial Phenomena: formation and resulting properties Preparation of emulsions Nanoemulsions Complex systems and formulation Encapsulation and applications Theme 3 : Behaviour, characterisation and processing The workshops organised under this theme reviewed new developments in methods for rheology or stability characterization, description and modelling. Workshops: New characterization techniques Structure, Rheology Stability, Flocculation Theme 4 : New challenges. New ambitions The three themes provided a response to the question identified in the title of the congress by “Developments”. This fourth group of workshops identified the ambitions resulting from these new challenges that emulsion uses have to face up to: the impact of the consideration of sustainable development requirements, new emulsification techniques, new strategies to stabilise interfaces. Workshops: Emulsions and sustainable development New emulsification processes New emulsifiers: new chemistry, polymers, particles