Stakeholder engagement (SE) is recognized as a key process to align firm and stakeholder interests and to identify material content for sustainability reporting (SR). Research on SE quality in an SR context has, however, been largely neglected. This paper investigates the current state and quality of SE within SR within a sample of 55 sustainability reports issued by European firms that used the new Global Reporting Initiative's G4 Guidelines. It will focus on why, how, and with whom firms are involved in SE based on an SE disclosures analysis framework and investigate the extent to which reporting maturity influences the state of SE disclosures and SE quality. While SE seems common practice, many firms are failing to provide full disclosure on how stakeholders have been engaged in defining report content. Less than half of the studied reports contained clear disclosures on how firms had responded to stakeholder concerns. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment