Recent debate about immigration policy has focused on whether or not immigrants' contributions to public revenues cover the costs of the public services they use, and if not, should the federal government reimburse state and local governments for those net costs. Findings of recent studies have varied widely, because of differences in data available, disagreements about the public services to be considered, and differing treatments of conceptual issues. Unless consensus is reached on a host of data, accounting, and conceptual issues, additional studies are not likely to provide definitive answers. To date, little has been established beyond the fact that most immigrants have low income, and that families with low income contribute less to public revenues. The suggestive finding is that illegal immigrants are net consumers of public services more because of low income than because of immigrant status. Recommendations are made for improved data collection and analysis. One figure and eight tables illustrate the discussion. Two appendixes list the studies reviewed and present four additional tables of summary results. (SLD)