During the last decades, the food, pharmaceutical and many other industries have seen several changes in packaging technology and applications because of new consumer demands and market trends. These drivers can be summarized as requirements for high quality, freshness and extended shelf-life of products, with easy-to-use and resistant packaging made with lighter, cheaper and recyclable materials. On the other hand, public demand and awareness for food safety has become a significant concern. This even intensifies on every outbreak of various bacteria in various area of the world, following the consumption of contaminated meat and cheese products. Those outbreaks prompted the public awareness to question food quality in stores and technological solutions that could prevent contamination and/or alert consumers, which may provide better public protection. The performance of polymer films and multilayer packages are the result of the microstructure that is imparted to the material as a result of complex interactions between the resin and the thermo-mechanical history that it experiences during processing. This microstructure is strongly influenced by molecular parameters of the resins used (molecular weight, molecular weight distribution, branching, co-monomer type and content, etc.), their layout in multilayer structures and the additives used as well as the rheological, thermodynamic, thermal properties and the crystallization kinetics under the processing conditions. In the past, most of the studies were directed to the improvement of structural properties of films and multilayer structures (mainly mechanical: strength, tear, toughness etc…) and much less interest was directed to functionality such as barrier, porosity, antibacterial, antimicrobial, oxygen scavenging, detection, biological interactions etc. In this presentation, the results of recent studies directed towards addressing those concerns will be presented and discussed.