q This issue of the Journal of Non-Newtonian Fluid Mechanics includes a series of papers based on work presented at the international workshop on Viscoplastic fluids: from theory to application, held Nov. 18–21, 2013 in Rueil Malmaison, France. A list of participants is provided in Table 1. This was the fifth biannual meeting on this subject. The previous meetings were held in Banff (Alberta, Canada), Monte Verita (Ascona, Switzerland), Limassol (Cyprus) and Rio de Janeiro (Brasil) [1]. Like previous editions, the aim of the workshop was to bring together leading researchers in the field of viscoplastic fluids across several disciplines to foster the awareness and the transfer of ideas, both from academic research and industry. The program consisted in a single technical session and three invited keynote lectures. A total of 49 talks and 9 posters were presented, spanning fascinating topics from the coating of a viscoplastic fluid on a plate to the numerical simulation of the transition of viscoplastic fluid flows to turbulence. The workshop enjoyed an unprecedented number of 80 participants (Fig. 1), a popularity that emphasizes that viscoplastic fluids are a ''hot'' topic in the field of non-Newtonian Fluid Mechanics. Invited speakers were John Tsamopoulos (University of Patras, Greece), Guillaume Ovarlez (Laboratoire Navier, Université Paris-Est, France) and Fabrice Toussaint (Lafarge Centre de Recherche, France). John Tsamopoulos opened the meeting with an invited talk on the numerical simulation of yield stress fluid flows and its applications to the problem of the rising of a single bubble. He both elaborated on the technical details of the numerical tools available nowadays for the simulation of this class of flows and provided insight on the effect of elasticity and pressure oscillations. On the second day of the workshop, Guillaume Ovarlez gave an overview on the rheological behavior of suspen-sions of particles and bubbles in a yield stress fluid, illustrating his findings with a large number of experimental results. On the third day, Fabrice Toussaint bridged academic research and industrial concerns in the field of concrete rheometry, ranging from the fundamental behavior of concrete slurries and their characterization in rheometers to the fascinating last i-Phone application designed to tell the truck driver how quick the concrete slurry properties are evolving in the truck's rotating drum while driving to the construction site. Standard talks ranged from experiments, theory to numerical simulations, with an emphasis on the rheolo-gical behavior of carbopol gels and the more general question of how to experimentally characterize yield stress materials with thixotropy, a question that has been mobilizing the attention of the yield stress community for a few decades. The realistic and accurate modelling of the behavior of viscoplastic and thixotropic materials still remains an unsolved question in the field, as already underlined two years before in Rio de Janeiro, but also progress has been made, with new measurement techniques as, e.g., low amplitude oscillatory shear (LAOS). In particular, the workshop featured intense discussions on thixotropy and its mathematical modelling. Efforts in designing new numerical approaches with enhanced accuracy and fast convergence have seemed to slow down and the workshop was an occasion to collectively acknowledge that this research direction should be revived. The workshop took place at IFPEN-Rueil Malmaison, in the suburb of Paris, France. IFPEN is a large national research center in the field of energy, with nice facilities and well designed services. The social program started with an ice-breaking cocktail in a French-style coffee shop named ''Café Leffe'' in the heart of Rueil Malmaison, which was a casual occasion to chat with long-term colleagues and enables new participants to VPF to immerse into the yield (no) stress community and yield to the pleasure of enjoying French wines and the warm and friendly atmosphere of