This chapter focuses on the aspect of Authoring in Adaptive Hypermedia from some of its different perspectives. It starts by showing the necessity of research in this area, then describes a new framework model for authoring of Adaptive Hypermedia, LAOS. Within LAOS, the adaptation model, which is the main aspect of adaptive hypermedia, is detailed into a separate model, LAG. The flexibility offered by the LAOS framework is analyzed and estimated. To illustrate the theory, the chapter describes an implementation of this framework, MOT, and test results. The chapter ends with conclusions and discussion on future trends.