The interaction of fluids and structures is an area of tremendous activity, most notably for low Reynolds number flows which are described by the Stokes equations. This regime, where the suspended structures are microscopic, is especially important to chemical engineering, materials science, soft-condensed matter physics, and biophysics. This course will focus on the interactions of fluids with microscopic objects, such as deformable particles, swimming microorganisms and “active” particles, and the collective behavior of these systems. Students will first be given a thorough foundation in the physics and mathematical description of the Stokesian flow regime as well as relevant matter on material elasticity. On the theoretical side it will include mathematical aspects such as singularity, boundary integral, and approximate treatments of the Stokes equations, as well as Faxen relations and treatment of many-body interactions. The classical elastica will be described with emphasis on “extreme mechanics” of buckling and opening. On the experimental side, material will include basic methods and modern microfluidic techniques for fabrication. Students will then learn many different aspects of the dynamics of flexible structures suspended in viscous flows. The viscous forces acting upon flexible objects can deform them, say through continuous bending or an abrupt buckling, and these deformations in turn modify the flow, leading to a highly non-linear coupling. This arises in modeling the flagellae or cilia involved in micro-organismal locomotion and mucal transport, in determining the shape of biofilm streamers, and in new methods of structure self-assembly. Microorganisms locomote in a variety of ways, singly and collectively, and in many kinds of environments. This example of fluid-structure interaction is a central example of “active matter”. Lectures will cover both theoretical and experimental aspects, discussing classical results as well as modern advances in understanding collective hydrodynamics, and the effects of confinement and complex media on motility. This course will give the possibility to the students to learn the state of the art of this still developing area. We have designed a program for the courses in which both experimental and theoretical aspects will be treated and that will provide students with a strong background on the fundamentals of the field as well as recent developments on open questions. The course is addressed to doctoral students and postdoctoral researchers in hydrodynamics, mechanics, materials science, applied physics and applied mathematics, academic and industrial researchers and practicing engineers.