Purpose - The purpose of this research is to present the findings of a longitudinal case study into the professionalisation of public relations practices and the institutionalisation of corporate social responsibility as a legitimate social and business arrangement. In doing so, there are implications for the dynamic relationship between practices and the professionalisation of public relations. Design/methodology/approach - A qualitative longitudinal study is used to examine the social construction of social responsibility in the Australian banking industry from 1999-2004 across two levels of analysis - societal expectations as institution, and practices of banking and public relations as action. Findings - The study shows that the case organisations shifted their public relations and communication practices during the period of the study. In response to the demands of publics, there was a central shift from a one-way perspective where organisations sought to influence and persuade publics of the appropriateness of their actions towards a two-way perspective where organisations needed to consult, negotiate and engage with publics. In doing so, this study suggests that there was a shift in the profession of how public relations was practiced, but also highlighted the changes to institutional arrangements about the legitimacy of social responsibilities of large organisations. Research limitations/implications - The study uses an interpretive perspective to understand the role and impact of public relations practice on societal change. Practical implications - This research examines the role of public relations practice in achieving longer term changes for organisations and society. This contributes a first step towards developing a theoretical understanding of the contribution of public relations practice to organisational success and therefore evaluation. Originality/value - This paper makes two central contributions. Firstly, institutional theory and the social construction of societal and business standards of legitimacy are used in a public relations context. Secondly, this paper shows the effects of the micro-level of analysis of public relations practices on the macro-level of the profession.