Composite materials designed to retain porosity usually have pore-structure specific application. Common man-made materials that exploit porosity include paper coatings, superconductors, nano-silicates and hydroxyapatite. Typical characteristics sought after include; capabilities of mass transfer and liquid retention, improved opacity, lighter weight, enhanced gloss, controlled spread and imbibition, and control of heat conduction. Though required for the enhancement of specific properties, porosity also has the drawback of reducing mechanical strength and stiffness. This chapter serves as an introduction to porous particulate-based composites. Included are the physical properties of minerals and their raw sources for excavation. Also described are the structures of packed particles and the physics of polymer spreading and dispersion. When combined, these effectively govern the geometrical characteristics of the resulting pore structures. Variations in polymer structure that arise through the presence and influence of particles are also explained. Following this section is a review on surface science, adsorption and wetting and the mechanisms of adhesion. To conclude the chapter, is a short discussion on the environmental footprint of particle-polymer composites such as are commonly designed to retain porosity. The primary focus in this chapter is on mineral-particle polymer-matrix composites with porosity.