Although medically underserved groups bear a heavy burden of cancer disease and governmental agencies have required inclusion of minorities and women in cancer clinical trials since 1993, many of these groups are underrepresented in cancer prevention or treatment clinical trials. To assess and enhance recruitment of underrepresented populations into cancer-related clinical trials, investigators and governmental agencies need consistent measurement approaches for recruitment that can be applied to diverse settings where trials are conducted. We conducted a systematic review to evaluate what measurement approaches were used to evaluate the success of recruitment of underrepresented groups into cancer prevention or treatment trials, and whether these recruitment goals were stated a priori. Only two articles reported an a priori recruitment goal. The recruitment measurement approaches varied considerably, with no consistent standard, especially for individual trials. By using the empiric evidence from this review in conjunction with the National Institutes of Health (NIH) guidelines, we constructed a framework for choosing consistent a priori recruitment goals for underrepresented groups based on the research question and study location. Using consistent measurement approaches for underrepresented groups will improve comparability of recruitment strategies across trials, improve equity in distribution of benefits and burdens of cancer-related clinical trials, and may improve applicability of trial results to multiple populations. Cancer 2006. © 2006 American Cancer Society.