Stauprimide is an enhancer stem cell differentiation into endoderm. In vitro differentiation of embryonic stem cells is of great interest to regenerative medicine, and current protocols are labor-intensive and expensive. Small molecules that induce or enhance differentiation are highly desired. High-content screening identified compounds that enhance endodermal differentiation in the presence of low levels of Activin A. Stauprimide increased definitive endodermal markers but not markers for visceral/parietal endoderm or mesoderm. Stauprimide-differentiated cells could be further differentiated into hepatocytes. Stauprimide treatment during differentiation decreased the concentration of Activin A required for definitive endoderm formation, and it eliminated the need for serum. The mechanism