There is an abundance of vaccines currently in development, with most of them exploring novel mechanisms, adjuvants and/or delivery systems not only for traditional prophylactic use, but also for therapeutic uses. As vaccines are generally administered to healthy individuals, ensuring their quality, potency and safety becomes crucial, especially prior to evaluation in humans. To ensure these key attributes, vaccine developers need to incorporate them as early in the development program as possible, starting in basic research and continuing through preclinical, clinical and postmarketing development. Fortunately for vaccine developers, ample guidance is available from various regulatory agencies to enlighten the long and arduous path of vaccine development. This review will highlight these regulatory expectations, and provide some clarity as to why they are in place.