Abstract: In this paper, we describe the design and implementation details of a software development framework for building Outdoor Augmented Reality (AR) applications on mobile platforms. The framework consists of a mobile client software library, web-based server, and a web-based authoring tool. It is developed using component based design making it easy to customize and reuse, and as it provides both low-level functional modules and ready-to-use high level components, both skilled and novice developers can choose the level of abstraction they need to use, or even work together under the same framework. By mixing and matching the ready-to-use framework components, developers can focus on designing and developing the domain content, logic and user interface, and spend less time implementing basic functionality. We demonstrate the validity of our framework with three case studies of mobile Outdoor AR application development.