The possibility of measuring and comparing sustainability performance is generally taken for granted in management studies and practices based on the evaluation, selection and ranking of the supposedly best companies in the field. The purpose of this article is to question this basic assumption by analyzing the comparability of sustainability performance through a systematic review of 12 mining company reports using Global Reporting Initiative (GRI) guidelines. The analysis of information based on 92 GRI indicators raises serious questions concerning the hypothesis of measurability and comparability of sustainability performance, drawing attention to the main reasons that make it very difficult if not impossible to establish a credible and justifiable classification among organizations.