The use of composite materials is ubiquitous in every field of human activities, including in the agricultural, industrial, environmental, biomedical and transport sectors. After a pandemic with the simultaneous unfolding of an energy and climatic crisis, we now realize how necessary it is to carry out studies on composite materials based on polymers to positively affect our current society and, in particular, future generations.To this aim, in the present selection of scientific articles we have given visibility to worthy contributions on a wide variety of topics, highlighting how essential plastic-based composite materials and their derivatives are in our daily lives. The articles in this Special Issue were wide-ranging and devoted to the properties and characterization of composites for innovative and strategic applications and, more generally, for the development of the chemical-physical properties of these materials.