Activities to reduce net greenhouse gas (GHG) emissions by biological soil or forest carbon sequestration utilize currently known and readily deployable technologies. Many other GHG emission reduction options require future technological development or must wait for turnover of capital stock. This paper reports an investigation of the competitiveness of soil carbon sequestration from multiple strategy viewpoints. Key factors affecting the competitiveness of terrestrial mitigation options are land availability and cost effectiveness relative to other options such as CO2 capture and storage, energy efficiency improvements, fuel switching, and non-CO2 greenhouse gas emission reductions.