Mangroves can sequester and store massive amounts of CO2 from the atmosphere in the form of live plant and detrital biomass. Large amounts of autochthonous and allochthonous carbon (C) are also stored in sediments, where waterlogged and anoxic conditions inhibit microbial breakdown of organic matter. As a result, C buried in sediments of mangroves can remain there for millennia if left undisturbed, making them critical long-term C sinks. These high levels of aboveground and belowground C stocks have elevated the importance of mangroves and other blue carbon habitats in climate change mitigation and adaptation as well as efforts to protect and restore them. While methods have been developed for quantifying and reporting C stocks, the environmental drivers that influence the accumulation and retention of C stocks in blue carbon habitats are lesser known. Identifying important drivers of C accumulation in blue carbon habitats will increase conservation and restoration efforts so that they can continue to mitigate climate change by offsetting greenhouse gas emissions. Successful restoration and conservation activities can also be used in nationally determined commitments or in voluntary C markets. This chapter will explore the biological, biogeochemical, and geomorphological drivers that influence C burial in mangrove sediments.