The past year has been a very active one in the field of gene transfer to hematopoietic targets, specifically stem cells and T cells. A number of clinical trials were published that both demonstrated progress as well as identified problems that investigators will face in trying to make the technology therapeutically applicable. Important laboratory and animal experiments focused on predictive models for human stem cell behavior, methods for culturing and expanding primitive cells ex vivo, immune responses against transgenes, in vitro and in vivo selection of transduced cells, and alternatives to standard retroviral vectors.