Self-adaptation is emerging as an increasingly important capability for many applications, particularly those deployed in dynamically changing environments, such as ecosystem monitoring and disaster management. One key challenge posed by Self-Adaptive Systems (SAS) is the need to handle changes to the requirements and corresponding behavior of a SAS in response to varying environmental condition during runtime. In this paper, we discuss the role of uncertainty in such systems, research challenges and present results from our experiences when tackling those challenges. We also review di erent modeling techniques for the development of self-adaptive systems with speci c emphasis on goal-based techniques.