To assess the current state of hospitals' infection surveillance and control programs (ISCPs) nationwide and to provide a sampling frame for selecting hospitals for later phases of the SENIC Project, the authors mailed a screening questionnaire in March, 1976, to virtually all US hospitals; 86% of those in the SENIC target universe responded. Of these, 64% (2299) reported that their ISCPs were being supervised by a physician or a microbiologist with special interest in infection control, and 42% had an infection control nurse (ICN), or equivalent, working at least half time. In contrast to the supervisors, most of the ICN's had recieved special training in hospital infection epidemiology and spent the majority of their time doing surveillance. Almost all hospitals (87%) had practiced some form of infection surveillance. Almost all hospitals (87%) had practiced some form of infection surveillance, with half reporting very active programs. Larger hospitals with ISCP staff tended to use active clinical casefinding methods, while smaller hospitals tended to use passive techniques. Most hospitals (76%) were collecting relatively large numbers of environmental cultures routinely, although a growing number (about 25%) had reduced or discontinued this practice. Routine culturing was more often performed in hospitals employing passive surveillance methods. Although the adoption of selected infection control policies and practices has varied widely, chronological data indicate that a major infection control movement has emerged since 1970.