The Millennium Development Goals (MDGs) represent an unprecedented global consensus about measures to reduce poverty. The eight goals address targets to increase incomes; reduce hunger; achieve universal primaryeducation; eliminate gender inequality; reduce maternal and child mortality; reverse the spread of HIV/AIDS, tuberculosis, and malaria; reverse the loss of natural resources and biodiversity; improve access to water, sanitation, and good housing; and establish eff ective global partnerships. Progress in some goals has been impressive; however, global targets will not be met in some regions, particularly sub-Saharan Africa and south Asia. As we approach the 2015 target date, there is considerable interest in assessment of the present goals and in consideration of the future of development goals after 2015. This Commission has brought together sectoral experts on diff erent MDGs from the London International Development Centre to identify cross-cutting challenges that have emerged from MDG implementation so far. This interdisciplinary approach diff ers from previous MDG studies that have either examined individual goals or made broad sociopolitical assessments of the MDGs as a development mechanism. We used our analysis of crosscutting challenges as the basis to identify a set of principles for future goal development, after 2015. We emphasise that this report is not an assessment of the MDGs; we focus deliberately on challenges with the implementation of the MDGs so as to inform future goal setting. The MDGs are an assembly of sector-specifi c and often quite narrowly focused targets that have their various origins in development ideas and campaigns of the 1980s and 1990s. They were not derived from an inclusive analysis and prioritisation of development needs, and this is refl ected in the absence from them of a range of key development issues. The variable progress recorded with goals and targets partly indicates a tendency over time to focus on a subset of targets that have proven easier to implement and monitor, or which have stronger ownership by international or national institutions, or both. Complexity and lack of ownership have been particular problems for new targets added later in the MDG process. We provide short analyses of each MDG for those seeking more depth and to set out the evidence for a cross-MDG analysis (webappendix). Clearly the MDGs have had notable success in encouraging global political consensus, providing a focus for advocacy, improving the targeting and fl ow of aid, and improving the monitoring of development projects. However, MDGs have also encountered a range of common challenges. Challenges with the conceptualisation and execution of the MDGs arise at the three discrete levels on which they are constructed: goals, targets, and indicators. The very specifi c nature of many goals, refl ecting their diverse, independent origins, leaves considerable gaps in coverage and fails to realise synergies that could arise across their implementation; we draw attention to particular synergies between education, health, poverty, and gender. In some cases, targets present a measure of goal achievement that is too narrow, or might not identify a clear means of delivery. Other challenges encountered by several MDGs include a lack of clear ownership and leadership internationally and nationally, and a problem with equity in particular. Issues of equity arise because many goals target attainment of a specifi c minimum standardreg, of income, education, or maternal or child survival. To bring people above this threshold might mean a focus on those for whom least eff ort is required, neglecting groups that, for geographical, ethnic, or other reasons, are more diffi cult to reach, thereby increasing inequity. From our cross-sectoral analysis, we conclude that future goals should be built on a shared vision of development, and not on the bundling together of a set of independent development targets. By means of example, we conceptualise development as a dynamic process involving sustainable and equitable access to improved wellbeing, which is achieved by expansion of access to services that deliver the diff erent elements ofwellbeing. These elements can be defi ned in many ways,and would include those addressed in the MDGs. Insteadof proposing a set of elements, and hence a new set ofMDGs, we suggest a set of fi ve principles by whichdevelopment should be achieved. A holistic approach isneeded to avoid gaps in the development agenda andensure synergy between its interlinked components,each of which should address elements of human, social,and environmental development. Elements of wellbeingshould be delivered to ensure equity of opportunity andoutcome, recognising its complex and local nature, andaddressing all communities while taking a deliberatelypro-poor approach. This equity is a key feature ofsustainability, as is a clear commitment to focusingproductivity growth where it is needed. A broaddevelopment agenda arising from this process should beagreed internationally, but developed locally, to ensureownership of goals and their monitoring across societynationally, regionally, and globally. This agenda shouldbe based on a strong global obligation supported byeff ective international institutional frameworks.Finally, we show how such principles can be applied tothe development of future goals by selecting one elementof wellbeing, health, and exploring the implications ofeach principle for its future improvement. © 2010 Elsevier Ltd.