Functional clothing can be divided into six categories: protective functional, medical functional, sports functional, vanity functional, cross-functional assemblies, and clothing for special needs. This chapter aims to present an overview of the various aspects such as design and development of functional clothing to counter chemical and biological terrorism. Considerable emphasis has been placed on functional clothing for EMI shielding, ballistic protection, development of superhydrophobic textiles for protection, textiles for chem-bio defense, and the implications of nanotechnology in developing protective clothing. The three primary mechanisms of EMI shielding include reflection, absorption, and multiple reflections. Sun-protective clothing: It is an item of personal apparel for which a claim of protective advantage against solar ultraviolet radiation is made. Emerging threats such as toxic industrial chemicals and oil spills present novel challenges in this regard. Ideal protective clothing provides wider protection capabilities, reduced logistic burdens, improved agility, and overall enhance the performance of the wearer.