The paper describes a practical approach which can be used by internal IT organizations to gain their business customers’ trust. The variety of customers of the internal IT service provider is limited to internal customers only. The distinguishing feature of the proposed approach is that it is completely practice-oriented, i.e. primarily aimed at building trust among IT service providers and their customers in a particular organization. The approach is based on the idea that there are measurable prerequisites for the emergence of a customer’s trust which allow you to partially formalize the IT organization’s intention to earn its customers’ trust. A model of intra-organizational trust is proposed; it is progressively improved as the IT organization develops its trust-building capabilities. The model comprises all IT service customers in an organization along with their communications and accounts for internal organizational IT service market specifics. A high-level blueprint of the trust model is described which can serve as a starting point when developing a full-scale trust model in a particular IT organization.
      We present an approach to the trust model improvement which builds upon principles adopted from widely recognized CMMI model. With this approach, an internal IT service provider can benefit from maturity assessment methods to improve its trust building capabilities.