A contact service in a municipality is a place where the citizens can apply for processing of their claims concerning municipal jurisdiction. Examples could be application for a place at pre-school, planning permission or change of dustbin etc. The clerks at the contact centre should be able to provide immediate service in most of the matters. This requires the work-process for each matter to be known. Before starting of a contact service this knowledge existed in the administration for the actual claim. In many cases it was tacit and not described. This paper discusses the problem of making this knowledge explicit and described in order to be used at the contact service. Issues concerning work organisation, personnel and job satisfaction are recognised, but not in focus. Instead our focus lies on the work content, processing of the claims, which the clerks are dealing with. It is a qualitative study, based upon three existing contact services and one, which is in the design phase. We start with a brief discussion of different types of knowledge, related to classical epistemologies within the organisation area (Nonaka & Takeuchi, Brown & Duguid, Cook & Brown, Polyani, etc). Based upon empirical material from the cases we identify some typical knowledge categories. It might be general knowledge about rules, procedures and such things; it might be experience-based knowledge from previous claims, typical claims and work praxis developed over time. It might also be knowledge about the specific citizen and about the specific application. But it can also be totally new categories. Two categories we are pretty sure to identify are matter-oriented knowledge, concerning the actual matter and procedural knowledge, concerning the processing of the matter-oriented knowledge. In our previous research about work-flow four levels have been identified and we suspect the same basic reasoning might apply here.