The 3rd International Multibody Summer School, jointly organized by Politecnico di Milano and University of Parma, will be held on 13-17 September 2021.Methods of multibody system dynamics represent a widespread, versatile and reliable approach to the simulation of engineering problems that involve the dynamics of complex mechanisms. Applications of these methods can be found in many fields, for instance in aerospace, automotive, virtual reality, biomechanics, AI, robotics and automation, to name a few.International experts will provide lessons and keynotes. This year it will be an ONLINE event: all students will use a teleconference system to connect to the workshop. A preliminary program with useful information is available at:http://www.multibodysummerschool.euThe invitation is open to PhD students, postdocs and researchers interested in multibody dynamics. The deadline for the pre-registration is June 30th, 2021.The official language of the school is English. A certificate of attendance will be provided to enrolled students. Workload: about 30 hours of lectures and laboratories, including hands-on, for a total of 5 ECTS.Alessandro Tasora, Università di ParmaPierangelo Masarati, Politecnico di Milano