In spite of its apparent stability, the network of support surrounding the Office’s claims to expertise in performance measurement should not be construed as permanent and un-problematic. Enrolment in a claim is not perpetual (Latour, 1999), and subsequent trials of strength will affect the stability of the Office’s claims. In our last interviews, several public servants still considered performance measurement to be more in the expertise domain of evaluators than that of accountants. Also, Canadian evaluators in the last few years have published in their association journal a growing number of articles that report on experiments carried out by evaluators in the area of performance measurement.26 In spite of its lower membership, program evaluation might in the future produce a network of literature persuasive enough to strengthen evaluators’ claims to expertise in understanding government performance, which could destabilize or reinforce the Office’s network of support. In 2001–2002 the Office employed a senior program evaluator in the expectation that she will, inter-alia, affect how it assesses performance measures.