Building on the foundations laid in Chap. 2, this chapter provides sustainability strategy consultants with a practical and methodologically sound guide to support clients in the development and execution of sustainability reporting activities. The chapter begins by detailing the process of conducting a Double Materiality Assessment, a cornerstone requirement of the Corporate Sustainability Reporting Directive (CSRD). This assessment compels organizations to evaluate sustainability from two complementary perspectives: Financial Materiality (outside-in): assessing how sustainability issues may affect the company’s financial performance; Impact Materiality (inside-out): evaluating how the company’s operations impact society and the environment. A clear explanation of EFRAG’s three-step process for identifying material topics is provided, along with a practical methodology for estimating both financial and impact materiality scores. This section equips consultants with the tools to guide clients in prioritizing relevant ESG topics and ensuring compliance with CSRD requirements. The chapter then explores stakeholder mapping and engagement, emphasizing its strategic importance in the materiality assessment process. Engaging stakeholders is essential for gathering insights into the organization’s most significant economic, environmental, and social impacts, risks, and opportunities. Practical approaches to stakeholder identification, segmentation, and consultation are presented to support effective and inclusive engagement strategies. Finally, the chapter concludes with a structured overview of the key components of a comprehensive sustainability report, including examples and templates to illustrate best practices.