An adaptive controller can be classified as identifier or non-identifier based, depending on the property of the adaptive strategy. Non-identifier based adaptive controllers adjust control parameters without explicitly estimating unknown parameters, but they generally lead to poor transient performance. Identifier based adaptive controllers can actively track system changes and tune control parameters to counteract them, but their stability and robustness bounds are difficult to check due to their nonlinear nature. As a result, the applications of adaptive control in safety sensitive systems are still very limited. The adaptive scheme developed in this book, referred to as safe adaptive control, is a combination of identifier and non-identifier based adaptive schemes, and is shown superior in performance and robustness than existing ones. In addition, using intelligent transportation systems as examples, it has also shown that conventional robust adaptive controllers can achieve desired performance in a safe manner. The theoretical and simulation results presented in this book will encourage more applications of adaptive control in safety sensitive systems.