Introduction: The purpose of this qualitative, exploratory study is to clarify ambiguous concepts in intelligence services literature specifically related to measurement of intelligence outcomes and impact. Method: Face to face interviews were held with five subject experts from various intelligence fields and countries regarding their conceptualizations of intelligence measurement. Participants were given the opportunity post-interview to review and edit responses, to ensure accuracy. Analysis: Participant responses were compared and contrasted in defining key terms, descriptions of current practice in outcome measurement, and requirements for future best practice. Results: Participants' definitions of terms and conceptual lenses varied. Participants' descriptions of their own practices in, and reactions to, measuring outcomes and impacts were unique to the participant and paralleled discussions in the literature. Suggestions for best practice were made. Participants agreed that improvements to current measurement practice are both possible and necessary, and called for conceptual developments in intelligence measurement. Conclusions: The authors intend this study to provide a starting point for comparative discussion regarding intelligence measurement, and the need for conceptual developments, in a field that has historically been dominated by prescriptive measurement models and unique accounts of measurement practice.