This communication reviews the participation of the Instituto de Astrofísica de Canarias (IAC) in the design of the European Solar Telescope. Apart of being the coordinator institution of the whole project, and, as such, responsible for the project managing, the IAC leads several tasks like overall instrument definition or characterization of the atmospheric turbulence profile with height or the definition of adequate detectors. More in particular, the IAC will design and build two long-base SHABAR (SHAdow BAnd Ranger), instruments to measure medium-altitude seeing. The IAC is also responsible for the design, together with other institutions, of the design of grating spectropolarimeters suitable for multiwavelength high spatial and spectral resolution.