An advertising agency is a project-structured organization, and knowledge-intensive business services with creativity and innovation are significant factors determining organizational success. Its organization and structure often change because of diverse projects, new technology, and new markets. Many advertising agencies grow and survive in the long run, creating sustainable competitiveness, while some fail and disappear. The question is why some advertising agencies can manage their strategy, organizational structure, and culture to gain access to environmental resources and achieve positive business results, while others fail to do so. The reason can be found in the fact that some advertising agencies know how to respond to a growing gap between the rate, amount, and complexity of change in the world and the ability of the organization to keep up. The concept of change management is moving from the traditional idea of a long-term process to change management skills reconciling external and internal realities. This doctoral dissertation explores change management in an advertising agency and the impact and context related to innovation that underpins the advertising agency's business. Scientific contributions are research instruments, variables adapted from the scientific literature for research purposes and the validity of scales examined for marketing communication societies, and a review of research results for the application of change management and innovation that contribute to new knowledge about change management.