In this chapter, I consider the status of the concept of general intelligence and its explanations with special emphasis on biological explanations. First, I discuss g as a scientific construct and itemize the objections that have been raised against g. Second, I consider cognitive explanations of general intelligence and whether or not such explanations are capable of explaining g. Third, I survey attempts to relate g to brain functioning and consider the acceptability of various explanations that have been proposed. The emphasis in this chapter is on the potential of explaining g.