The analytical approach, which lies at the basis of the exact and natural sciences, rests on the notion that complex systems can be reduced to simple components. This divide-and-conquer approach has shaped contemporary science and technology, and has formed the foundation for virtually all scientific breakthroughs in the 19th and 20th century. It is also the origin of the separation of mechanics into fluid and solid mechanics, so much so that these branches of mechanics are commonly considered as distinct scientific disciplines. Notably, the disconnection between fluid and solid mechanics is evidenced by the tremendous advancements in computational methods and commercial simulation codes for fluid-and solid-mechanical systems separately, as compared to the relative underdevelopment of commercial codes for fluid-structure-interaction analyses.With the advancement of analysis capabilities for fluid-and structure-mechanics systems separately, emerged the realization that many problems in science and engineering cannot be appropriately categorized as either a fluid or structure problem, but are fundamentally determined by the interaction of a fluid and a solid. Examples are flutter and buffet instabilities in aerospace and civil engineering, the functioning of heart valves in biomechanics, sloshing and vibrations in flexible fluid containers and fluid conduits, deployment of inflatable structures such as airbeams and airbags, and deformation of soft substrates due to capillary forces, for example, in microfluidic applications and biomechanics. The development of computational methods for fluid-structure-interaction problems commenced in the early 1980s and many important foundations were laid in the 1990s. Despite the significant progress that has been made since then in computational models and methods for Fluid-Structure Interaction (FSI), many open challenges still remain, and computational FSI continues to be an active area of investigation and development.This special issue presents an overview of vanguard developments in computational methods for fluid-structure interaction. The 12 manuscripts in this special issue cover a variety of contemporary topics in computational FSI.The development of efficient and robust partitioned solution methods continues to be an important branch of research in computational FSI. Such partitioned solution methods allow to retain the modularity of the fluid and structure subsystems, thus enabling the reuse of the complete gamut of advanced commercial and open-source simulation software for fluid-dynamics and solid-dynamics problems separately. In this special issue, Cao et al. present a spatially-varying Robin coupling condition to mitigate the added-mass effect of incompressible flows in FSI in partitioned solution procedures. 1 In a similar vein, Dettmer et al. present a new combined two-field relaxation strategy to enhance the stability of the standard Dirichlet-Neumann FSI coupling strategy in the presence of strong added-mass effects. 2 The work by Rüth et al. is concerned wit...