An accessible way to monitor company sustainability, is to study sustainability reports. In spite of wide adherence to the extensive Global Reporting Initiative standards, sustainability reports still vary considerably regarding how well these are integrated and used. The purpose of this paper is to present and test a maturity grid for sustainability reports assessment that enables critical stakeholder needs analysis of sustainability reports. Based on a stakeholder needs perspective we argue that the right thing in a sustainability report means reporting in the entire value chain for main sustainability impacts. Doing this right means having externally set targets for main sustainability impacts, using relevant absolute and relative indicators, and having an easy to read report presenting main performance compared to targets for a period of at least seven years. Some 50 sustainability reports from Swedish companies in various industries were collected and assessed using the maturity grid. Results indicate that the maturity grid is usable, but that the sustainability report assessment still is difficult, and that variability of the assessments are high. Furthermore, the observed indicative levels of measurement maturity in organizations are low suggesting that most companies still are struggling with understanding what sustainability means to them.