Abstract: The Australian Defence Force (ADF) is progressing the development of a joint capability for intelligence, surveillance and reconnaissance (ISR). The premise for its evolution has been derived from anecdotal operational experience, the lead of the United States, and ADF's Network Centric Warfare concept. There is, however, no specific requirement yet stated and endorsed for what such a capability will practically deliver, particularly as an operational outcome. As an integrating capability, joint ISR is envisioned as providing considerable value-add to the individual ISR operations that are routinely conducted using systems owned or accessed by Defence. This is not different to the rationale for any form of joint operation, that combining systems from a range of environments permits the undertaking of more complex missions with improved likelihood of success. This paper examines the capstone doctrine for joint military operations, Joint Operations for the 21st Century, and develops capability guidance for the integrated ISR capability in terms of the key force attributes of Reach, Know, Exploit. The paper also discusses how Defence ISR must consider expanded utility across the options Government has available to employ. By developing this alignment, a clear operational purpose for a joint ISR capability and the characteristics of future ISR systems are described.