Last month's London Summit on Family Planning, hosted by the Bill & Melinda Gates Foundation and the UK government's Department for International Development, has been hailed as a resounding success. A total of US$2.6 billion was pledged to provide 120 million women and girls in developing countries with access to family-planning services by 2020. In measuring the success of this welcome campaign, the delivery of social change should also be taken into account.

The hosts emphasize that results will be rapid and quantifiable, for example in terms of the number of contraceptives supplied. But reducing unwanted pregnancies requires other improvements in women's lives, such as better education for girls and reduced child mortality (J. Drèze and M. Murthi Popul. Dev. Rev. 27, 33–63; 2001), outreach by community-health workers and women's empowerment (see, for example, go.nature.com/bpjgma), and quality family-planning programmes. Such factors are harder to quantify.

Focusing simply on what can be measured encourages short-term, narrow interventions rather than broader, longer-term strategies. For instance, value-for-money criteria make it tempting to sidestep national health-care systems, when supporting these is crucial to the delivery of appropriate technologies in developing countries.