The purpose of this article is to compare four different levels of aggregation to assess their utility as areal units in child maltreatment research. The units examined are county, zip code, tract, and block group levels. Each of the four levels is analyzed to determine which show the strongest effects in modeling the correlation between poverty and child maltreatment report rates. Tract-level aggregation appears to be the most generally robust level, with other levels of aggregation being more vulnerable to different kinds of threats. Some zip codes contain very few people, raising reliability issues, but if weighting or minimum population cutoffs are used, this problem is minimized, and zip codes become an attractive choice. County-level data are less homogeneous than other levels, introducing validity concerns. The smaller populations commonly present in block groups also invoke reliability problems, reducing their utility, especially when rare events are examined.