Wearable devices have the potential to be used for monitoring, augmenting, assisting, delivering content, and tracking in both individual and organizational contexts. Despite this potential, previous studies indicate that the abandonment rate is quite high relative to the usage rate due to usability factors. This chapter provides a comprehensive systematic literature review on the usability issues related to wearable devices, as well as recommendations for overcoming the identified problems. It also investigates and presents a survey of the existing usability evaluation methods used to identify and evaluate the usability of wearable devices, including their strengths and limitations. As such, we present a categorization framework that gives an overview of the overall usability issues that act as the barriers to user adoption and a summary of which types of usability issues are associated with which type of device category. The chapter has the potential to inform and assist researchers, practitioners, and application developers as they work toward developing, implementing, and evaluating wearable devices and their associated interfaces, and this, in turn, may assist with sustained engagement among users.