IAU Commission 35 consists of members of the International Astronomical Union whose research is concerned with the structure and evolution of stars in all parts of the H-R diagram. Their interests range from various aspects of stellar interior physics, such as convection, diffusion, rotation, magnetic fields, to asteroseismology and the prediction of the evolutionary and nucleosynthetic histories of stars that are of vital importance for our understanding of stellar populations and galactic chemical evolution. This report presents some highlights that were published during the present triennial term and which concern the field of Stellar Constitution.