The ionic layer-by-layer assembly technique, introduced by Decher in 1991, has emerged as a versatile and inexpensive method of constructing adaptive or responsive polymeric thin films, with physico-chemical control of ionized species. Films formed by electrostatic interactions between oppositely charged poly-ion species to create alternating layers of sequentially adsorbed poly-ions are called “Polyelectrolyte Multilayers (PEMs)”. PEMs have long been utilized in such applications as sensors, eletrochromics, and nanomechanical thin films but lately they have also been shown to be excellent candidates for biomaterial applications due to 1) their biocompatibility and bioinertness, 2) the ability to incorporate biological molecules, such as proteins, and 3) the high degree of molecular control of the film structure and thickness providing a much simpler approach to construct complex 3D surfaces as compared with photolithography. The development of new methods for fabricating physico-chemical thin films that can provide adaptability, chemical functionality, controlled morphology, wetting property, and biomolecular adhesion will be presented. These films could lead to significant advances in the fields of tissue engineering, drug delivery and biosensors which have become increasingly germane applications in the field of chemical engineering and materials science.