Supporting organizations in their decarbonization journey is a critical responsibility for sustainability strategy consultants, requiring a robust set of tools, methodologies, and sector-specific insights. This chapter introduces the essential instruments and approaches that consultants can leverage to guide companies through the complex process of reducing greenhouse gas (GHG) emissions, aligning sustainability objectives with long-term business value creation. This chapter begins by outlining the foundational step in any decarbonization strategy: the assessment of the company’s carbon footprint. This includes a detailed presentation of the key steps of the Life Cycle Assessment (LCA) methodology and the GHG Protocol, which provide standardized approaches for calculating emissions across Scopes 1, 2, and 3. Establishing a reliable emissions baseline is essential for setting meaningful reduction targets and tracking progress over time. Building on this foundation, this chapter introduces the Science-Based Targets initiative (SBTi), a globally recognized framework that enables companies to set emissions reduction targets in line with climate science and the goals of the Paris Agreement. Consultants play a key role in helping organizations interpret and apply SBTi criteria, ensuring targets are both ambitious and achievable. A critical aspect of decarbonization planning involves identifying emissions hot spots and prioritizing interventions. This chapter presents tools such as Marginal Abatement Cost Curves (MACCs), which help organizations evaluate the cost-effectiveness of various mitigation options and allocate resources strategically. In addition, this chapter explores the carbon credit market, which allows entities—governments, companies, or institutions—to buy and sell carbon credits, each representing the right to emit one metric ton of CO2 or its equivalent in other GHGs. Consultants must understand the structure, regulatory context, and strategic implications of carbon markets to advise clients on how to integrate offsetting mechanisms into their broader net-zero strategies.