Intellectual capital (IC) development includes a wide set of activities focusing on the improvement of an organisation's intangible resources. However, it is often unclear what kind of impacts different IC initiatives have. The current literature lacks appropriate methods for identifying and measuring them. If it is not possible to assess the impact of various development activities it is difficult to justify IC investments or choose between alternative service providers. This paper, based on a case study, examines how to assess the impacts of an IC development initiative. The empirical research setting is the Pietari Business Campus, a knowledge‑intensive business service organisation providing various development services for its twelve member companies operating in the St. Petersburg region in Russia. In this paper, the literature is first examined to understand how the impacts of development activities can be assessed in different contexts. The characteristics of these approaches are then utilised to formulate the assessment methodology used in the case study. The empirical assessment consists of both numerical indicator data and subjective interview data. The case study showed that the activities and outputs can be measured quite accurately but that the outcomes are difficult to capture. The main challenge results from external changes taking place and making it difficult to observe the outcomes of development activities. Due to the challenging nature of the assessment task and the relatively low managerial priority of the issue (on the customers' side) it is suggested that subjective assessment methods may provide sufficient information in many cases. Although this paper is focused on IC development, there may be similar contexts in other knowledge‑intensive services in which the lessons of this study might be useful.