Recent research carried out under the ‘third wave of science studies’ has produced robust categories of expertise, and has developed normative ideas about how it should be used during controversies over technological decision-making. Though separate in the literature, third wave ideas about contributory expertise appear to be compatible with the recent ‘turn to ontology’. Both sets of ideas focus on what it is that practices are able to produce, and consider the results of those practices to be real. It is argued here that contributory expertise can usefully be treated as an ‘object’ under the ontological framework, thus placing additional analytical focus on the practices that are used to enact it. To explore this idea, documentary analysis and qualitative interviews have been used to produce a description of cryptology research and the crypto wars in the United Kingdom from 1970 to 2000. The cryptology research carried out at four research sites will be described. It is argued that, given divergence amongst the institutional research practices used at each site, the contributory cryptology expertises enacted during this period were ‘multiple’, and can be identified as such using sociological discrimination. A description of how these expertises were then used during the crypto wars - a subsequent controversy over the regulation and use of cryptography in the 1990s - is also provided. It is argued that, as a consequence of this multiplicity, expertises were used during the crypto wars in different ways and for different purposes. In particular, the consequences of basing political decisions on expertise enacted in secret are described. It is argued that acknowledging multiplicity amongst contributory expertise could be used to improve the application of ‘elective modernism’, and to refine its core tenets through the application of a ‘Minimum Transfer Requirement’ and the identification of the ‘problem of expert discrimination’.