This article examines how socioeconomic deprivation relates to child Supplemental Security Income (SSI) participation in local areas. The authors construct a deprivation index that reflects a range of socioeconomic factors. They find that local areas with higher deprivation generally have higher levels of child SSI participation, but there is substantial geographic variation. To explore this variation, the authors assess the demographic and economic factors associated with the deviation between observed child SSI participation and a level of participation predicted by the deprivation index. Local areas in which child SSI participation is substantially lower than the deprivation index predicts might be promising targets for outreach to better inform families about the SSI program. By measuring the deviation between predicted and actual SSI participation at the census tract level, outreach efforts can pinpoint the precise locations where they might plausibly have the greatest effect.