Peripheral displays are an important class of applications that improve our ability to multitask. The main contribution of this dissertation is to provide knowledge for designing and evaluating glanceable peripheral displays to support multitasking. Glanceability is critical to enabling quick intake of visual information with low cognitive effort. However, not enough is known about how to best design glanceable visuals for performance-oriented peripheral displays. We first demonstrate that peripheral displays can improve important multitasking needs for users. We then contribute a set of best practices for designing glanceable peripheral displays, using the wealth of abstraction techniques (e.g., change detection, feature extraction), design variables (e.g., color, shape), and design characteristics (e.g., complexity, symbolism) available. We also contribute an evaluation framework that clearly defines peripheral displays, proposes criteria for evaluating their success, and describes approaches for evaluating these criteria for different types of peripheral displays. Applying the design and evaluation knowledge presented in this dissertation to peripheral displays will improve our ability to manage multiple, ongoing tasks through low-effort monitoring.