Processes and systems related to solid phase peptide synthesis are described. The processes include a flow-through process comprising cyclic addition of amino acids to a column packed with resin, wherein each cycle includes the combination of the amino acids with one or more reagents to provide an activated amino acid mixture, and wherein heating is applied to the amino acid(s) before they are passed through the column and wherein the amino acids are re-circulated at least once over the column packed with resin. Systems for such processes are also described.