Abstract: Originated from financial reporting context, the concept of materiality has been applied in and contributed to sustainability reporting, by identifying, selecting, and prioritizing sustainability issues with significant impacts. This paper identifies two dilemmas that traditional stakeholder-approach confronts, and then analyzes how materiality-approach delivers advantage by addressing the dilemmas. This paper further observes two challenges for materiality-approach reporting: complexity interrelationship of sustainability issues; and subjectivity in materiality assessment. It argues that the two challenges are inherent and basic concerns for current sustainability accounting. This paper concludes that the road of materiality to sustainability reporting would be advanced with the progress of coping with the challenges. That is, extending our insight on the complex interrelationships of sustainability issues, and on subjectivity in materiality assessment, we would not only embrace a better materiality model to future effective sustainability reporting, but also open a door to view the fundamental theoretical concerns in contemporary sustainability accounting.