The recent decline in the incidence of the SIDS in the District of Columbia has permitted identification of what appears to be two separate groups of cases within the generic SIDS population. While deaths of bed-sharing victims remained relatively constant throughout the study period, a greater than fourfold decrease was seen in non-bed-sharing SIDS fatalities. The implications and preliminary nature of these findings are discussed in an attempt to stimulate further inquiry into the possible safety hazard of the practice of bed-sharing in the SIDS age group and its potential influence on the incidence of the SIDS.