This review found no sources of straightforward indicators for use in measuring diplomatic influence. The literature and evaluations found to recommend the use of tailor-made evaluations to account for “differences in diplomatic settings, diplomatic activities and policy fields”. They hinge on developing a theory of change alongside questions and evaluation criteria that are context-specific. They rely on assessing intermediate goals as a ‘proxy’ for the immeasurable long-term influence, and causal contributions (contributed to a result) rather than causal attributions (caused a result). It was also frequently mentioned that programme designers tend to design programmes to support diplomatic influence without specific and measurable objectives because influencing processes are by nature non-linear. In these cases, evaluations will be correspondingly unable to provide specific and measurable indicators of achievement.