Resumen: Animals, including humans, have evolved a sophisticated mucosal immune system. By understanding mucosal immune activation, we can rationally design adjuvants to elicit a long-lasting protective immune response. In this chapter we will discuss about what is known about mucosal immunity and oral adjuvants. In particular, we will specially focus on polymeric nanoparticles as mucosal adjuvants that have been developed to stimulate lifelong memory for vaccination purposes