Lately, the notion of capability has emerged in IS engineering as an instrument to context dependent design and delivery of business services. Representing core business functionalities of an organization, capabilities, and capability driven IS development can be seen as both – a shift beyond and complement to the widely established service-oriented engineering paradigm where needs of customers form the leading modeling and design perspective. To ensure the needs of business stakeholders for variety of business contexts that an organization faces, and thus facilitate successful systems delivery, capability- driven development needs a well-defined method for requirements engineering, as well as its confirmation in practices. In this paper a process for specifying requirements capabilities and their designs is proposed. An application of the proposed approach to the area of business process outsourcing (BPO) services is carried out for the German company SIV.