Triacylglycerols (TAGs) stored in adipose tissue are by far the largest site of energy storage. Adipocytes continuously synthesize and break down these TAGs depending on the body energy status and its hormonal environment. They act as a “buffer” for plasma lipids and also for lipids stored in other tissues. This chapter presents the metabolic pathways used for adipose tissue TAG synthesis and breakdown and the way they are controlled. It points out important recent findings that have modified our conception of these pathways and of their regulation—particularly the role of glyceroneogensis in TAG synthesis—of proteins associated to lipids droplets—particularly perilipins—and of lipases other than the classic hormone-sensitive lipase in TAG hydrolysis.