Today, companies are expected to disclose corporate activities in an accountable, honest and hansparent manner. In this context, sustainability ıçorting is aıı important tool for communicating organisational trrrformance related to economic, social and environmental issues. This chapter identifies the performance indicators disclosed by Turkish pivate corporations. Within the framework of indicators defined by lhe Global Reporting Initiative (GRI), 29 sustainability reports were malysed to identiff the most commonly reported items. The findings üow that 1 8 sustainability reports based on the GRI 3. l standards mostly fulfil the requirements related to economic, social and environmental performance indicators. These findings afe not limited to specific sectors of the industry. Analyses show that corporations from enerry, fnancial services, food/beverage products arıd health care products/services scored quite well, while coıporations from the aviation and logistics sector lagged behind. According to the results, multinational companies are still the locomotives of sustainability practices and ıeporting, while only large Turkish organisations seem to dare or eadeavour for standardized reporting.