Some lactic acid bacteria (LAB) secrete a polysaccharide polymer. This extracellular polysaccharide, or "exopolysaccharide" (EPS), is economically important because it can impart functional effects to foods and confer beneficial health effects. LAB have a "Generally Recognized As Safe" (GRAS) classification and are likely candidates for the production of functional EPSs. Current challenges are to improve the productivity of EPSs from LAB and to produce EPSs of a structure and size that impart the desired functionality. The engineering of improvements in these properties will depend on a deep understanding of the EPS biosynthetic metabolism and of how the structure of EPSs relates to a functional effect when incorporated into a food matrix.