This doctoral dissertation investigates PR professionalism and PR as a strategic expert function. The approach is phenomenographic and the research progresses through four phases: (1) building a conceptual framework, (2) conducting an interpretative study of concepts, (3) conducting semi-structured in-depth interviews among 37 Finnish PR experts, and (4) constructing a holistic model of PR professionalism. The interpretative study of concepts concludes that PR professionalism consists of expertise in management of identity, management of public sphere, and management of relationships, and its core values are respect, responsibility and reflexivity. The interview study outlines five different approaches to the PR professional: Bridge builder, Advocate of the organisation, Advocate of the mission, Strategic facilitator, and Neutral facilitator. The critical differences in PR professionals’ thinking regarding their profession relate to the main goal of PR, its position and how the demand for recognition is reasoned, nature of communication, general orientation, and relation to ethics. The holistic model of PR professionalism consists of three intertwined and inseparable dimensions – the role, the goal and the soul of the professional PR – which enable and empower PR to ascend to its full potential as a strategic expert function. Through these dimensions PR professionalism facilitates communicative organisation and bridges the organisation with its environments, guides the PR profession to goal-oriented and high quality practice, and supports individual practitioner’s competence and professional identity.