The results of three population-based studies on violence against women in Nicaragua are compared in this article. Two of the studies were regional in scope (León and Managua) and focused specifically on women's experiences of violence, whereas the third study was a Demographic and Health Survey (DHS) conducted with a nationally representative sample of women. The lifetime prevalence estimates for women's undergoing physical violence from a partner were significantly higher in the León study (52 percent) and Managua study (69 percent), compared with that given in the DHS (28 percent). Possible explanations for the differences are examined through pooled multivariate logistic regression analysis, as well as analysis of six focus-group discussions carried out with field-workers and staff from the three studies. The most important differences that were found concerned ethical and safety procedures and the interview setting. The results indicate that prevalence estimates for violence are highly sensitive to methodological factors, and that underreporting is a significant threat to validity.