This article focuses specifically on the ascertainment of "invention" in inventorship disputes which arise from joint innovative engagements. Joint inventorship gives rise to several questions including: what the invention consists of; the quantum of collaboration supplied by parties; what significant contributions have been made by the respective parties; and whether there has been joint conception. This paper is concerned only with the definition and identification of "the invention" in patent entitlement disputes. It argues that the sum of inventive concepts disclosed in the specification, rather than the claims, should be the touchstone for determining of what constitutes the invention in such contexts. This article submits that the technical details contained in the specification should be preferred to the claims when one is considering inventorship in such cases because: a) the disclosure contained in the specification predates the claims; b) the claims derive their existence from the specification’s disclosure; c) the specification provides the technical background through which the claims could be understood in circumstances of ambiguity; d) the specification serves as a measure of proportionality between a protection sought and the technical contribution furnished; and e) the specification avoids inequitable assertions of entitlement in inventorship disputes.