PURPOSE: The relationship between cancer screening activities in Europe and the health systems in which they are embedded varies, with some screening programs organized largely separately and others using existing health service staff and facilities. Whatever the precise arrangements, the opportunity for screening to achieve health gain depends on many elements interacting within and beyond the health system, from an accurate register identifying the target population to a means to ensure and monitor follow-up. METHOD: A conjoint analysis was undertaken with 66 cancer screening experts from 31 countries taking part in EU-TOPIA (towards improved screening for breast, cervical and colorectal cancer in all of Europe) to identify priorities for an effective screening program, taking a whole system perspective. Ten attributes, each with two levels, were derived from a review of the literature and consultation with experts in cancer screening. Statistical software generated 12 profiles that were ranked by respondents and analyzed using standard conjoint analysis. FINDINGS AND CONCLUSION: The most important attributes were having up-to-date and evidence-based guidelines, followed by mechanisms for systematic monitoring of screening uptake, having a population register covering all of the eligible population and monitoring long-term outcomes. In discussions about the results, participants argued that quality assurance and adherence to guidelines were important, even though they generated low scores in the experiment. This difference may be due some attributes being interrelated, more wide-ranging or the sequential nature of establishing an effective screening program, with guidelines being the first stage of the process.