This chapter further tests the aiming big hypothesis by tracing the origin and evolution of four ELOs that certify carbon neutrality or carbon reduction efforts: The Carbon Trust, The CarbonNeutral Company, Enviro-Mark Solutions, and Carbonfund.org. Through comparative case studies and careful process tracing, illuminated by both interviews and primary document research, the chapter demonstrates that the decision to target large firms in global markets explains superior adherence to best practices in The CarbonNeutral Company and Enviro-Mark Solutions. Conversely, the narrow regional focus of The Carbon Trust and Carbonfund.org explains their comparative lack of best practice adherence. The cross-case comparison proves that a focus on the targets of governance offers more explanatory leverage than a focus on public versus private ownership or for-profit versus not-for-profit structure. The chapter concludes with implications for strengthening the credibility of carbon labels in the future.