This paper discusses a new approach to modeling organization populations containing knowledge-intensive service organizations. Knowledge-intensive services are a growing sector both in volume and in economic importance. In many aspects they are distinctive and do not fit to the traditional concepts explaining a business organization. Thus they benefit of new ways to interpret and study organizations and organization populations. This paper presents the concept of business ecosystem, and the agent-based modeling of it, as a possibility to understand the complex environment where knowledge-intensive service (KIS) organizations operate. This paper covers the distinctive features of knowledge-intensive service organizations first and then explains how these features can be taken into account when modeling a population of organizations containing KIS organizations as agents. This research is based on literature review and thus the conclusions are on the conceptual level.