In product line engineering, the application requirements engineers have to assure both a high degree of reuse and the satisfaction of stakeholder needs. The vast number of possible variant combinations and the influences of the selection of one variant to different requirements models is a challenge for the consistent reuse of product line requirements. Only if the requirements engineers are aware of all product line capabilities (variabilities and commonalities), they are able to decide whether a stakeholder requirement can be satisfied by the product line or not. In this chapter we present an approach for the development of application requirements specifications. In our approach we use the concept of orthogonal variability modelling and scenarios to support requirements engineers during the elicitation, negotiation, documentation, and validation of product line requirements. In this chapter we describe the application and benefits of the presented approach for all requirements engineering tasks in application engineering. Finally, the use and the applicability of the approach are discussed in the end of this chapter.