Ubiquitous learning is an emerging research field, allowing students to learn anywhere and anytime. Adaptivity and personalization issues play an important role in ubiquitous learning systems, enabling those systems not only to allow learners to learn whenever and wherever they want, but also in a personalized and adaptive way, considering the situation, characteristics, and needs of learners. In this paper, an overview of adaptivity and personalization issues in ubiquitous learning systems is provided and current and future research directions are discussed.