Amino acid transfer across the placenta is an important determinant of fetal growth and fetal growth restriction is associated with impaired amino acid transport. Transfer of amino acids across the placenta requires transport of amino acids across the apical microvillous (MVM) and basal (BM) membranes of the placental syncytiotrophoblast. Individual amino acids are transported across membranes by specific amino acid transport proteins. However for the placenta to take up all the different amino acids it requires and to transfer them to the fetus it requires interaction between different classes of amino acid transporter. On the MVM accumulative transporters and exchangers must interact to mediate uptake of all the amino acids required by the placenta. On the basal membrane amino acid exchangers must interact with facilitated transporters to transfer amino acids into the fetal circulation. The interaction between different amino acid transporters creates complex interdependencies which mean that it is not easy to predict how changes in one amino acid transporter will affect the activity of the system as a whole. Amino acid transporters can be regulated by a range of maternal signals including plasma nutrients and hormones. Within the placenta these signals are mediated via intracellular signaling mechanisms such as mTOR or by epigenetic regulation such as DNA methylation and microRNAs. The activity of amino acid transporters may be regulated by multiple regulatory signals. An important area of research is to determine whether transporters are regulated coordinately or whether they are regulated independently within the placenta. Understanding amino acid transfer and its regulation will therefore require an integrated approach not only to the mechanisms mediating the transport but also to multiple regulatory signals which determine the activity of amino acid transporters.