Between 1998 and 2009, research being conducted using human embryonic stem (hES) cells expanded primarily using private funds because of restrictions on the use of federal funds for such research. With limited federal involvement, privately funded hES cell research was being carried out under a patchwork of existing, and even inappropriate, regulations that neglected the many ethical, legal, scientific, and policy issues of concern to the public. This report provided guidelines for the conduct of hES cell research to address both ethical and scientific concerns to enhance its integrity by encouraging responsible practices in the conduct of that research.