Interest in abortion research is reemerging, partly as a result of political changes and partly due to evidence of the contribution of induced abortion to maternal mortality in developing countries. Information is lacking on all aspects of induced abortion, particularly methodological issues. This article reviews the methodological dilemmas encountered in previous studies, which provide useful lessons for future research on induced abortion and its complications, including related deaths. Adverse health outcomes of induced abortion are emphasized, because these are largely avoidable with access to safe abortion services. The main sources of information are examined, and their relevance for assessing rates of induced abortion, complications, and mortality is addressed. Two of the major topics are the problems of identifying cases of induced abortion, abortion complications, and related deaths, and the difficulties of selecting a valid and representative sample of women having the outcome of interest, with an appropriate comparison group. The article concludes with a discussion of approaches for improving the accuracy, completeness, and representativeness of information on induced abortion. Although the prospects for high-quality information seem daunting, it is essential that methodological advances accompany program efforts to alleviate this important public health problem.