Whilst the potential of blended learning to provide cost effective and quality learning experiences in adult education is generally acknowledged, deciding 'what to blend?' and 'how to blend?' is challenging. The design and implementation of blended learning is specific to the learning situation. Given the range of possible learning situations and the wide array of possible tools there are virtually endless possibilities for the blended learning designs. Those first embarking on blended learning ventures are faced with the task of surveying the vast quantity of resulting literature to gain a fundamental understanding of the concept and its implementation. For those beginning to implement blended learning in adult education contexts, this chapter attempts to provide a starting point for further exploration. This chapter seeks to lay foundations for understanding the concept of blended learning by firstly defining the term, and then highlighting key design concepts by discussing appropriate philosophical foundations and instructional design principles. An overview of some of the existing models and frameworks for blended learning in adult education is then given. Finally, some of the advantages and challenges of blended learning are discussed and future directions and research issues are identified