If you're trying to solve a problem, the scale of the proposed solution needs to match the scale of the problem itself. BRAC (formerly Bangladesh Rural Advancement Committee) began as a small relief effort in a remote part of Bangladesh after the 1972 war of liberation, but early on, we established an institutional mentality that focused on the scalability of interventions. We designed our interventions with the bigger, global problem of extreme poverty in mind. BRAC has become perhaps the world's largest NGO—actually more like a social enterprise hybrid—touching the lives of an estimated 135 million people.

BRAC has pursued two main pathways to grow impact to a transformative scale. One is to directly multiply what works, millions of times over, balancing both scale and localism. Our organization's disciplined program development process makes this possible. It first pilots a solution to ensure that it is effective, and then perfects the operational model to make it ultra-efficient. The result is effective, low-cost interventions in health, education, and livelihood development that are rooted in community demand and context, and that can spread to a great many other people. But such "massification" is not the only way to achieve transformative scale. The second pathway is to scale an approach with and through others. These two options are not mutually exclusive and can combine effectively.

For example, BRAC started its primary education program in 1985 in Bangladesh, responding to demands from landless parents that their children have access to the same sort of basic numeracy, literacy, and problem-solving classes BRAC was already conducting for adults. The government schools system wasn't reaching these youth, the poorest children in the villages.

BRAC created an education program for these children, drawing teachers from the ranks of the poor themselves and focusing on teacher training. This approach supported the local economy, helped ensure teacher commitment, and kept costs very low. In selected villages, the program gave local women a standardized, two-week crash course on student-centered learning in the Freirean Pedagogy, a clean break from the drudgery and rote memorization of state schooling. On-the-job training and supervision, and monthly refreshers with a peer group followed.

The model worked. Women who hadn't finished high school showed that they could learn and implement the basics of effective teaching. Dropout rates at BRAC schools were almost nonexistent. Moreover, parents proved willing to make financial sacrifices to give their children the chance for a better future. As a result, the final program was eminently scalable. BRAC now runs the world's largest private, secular educational system, with 1.1 million children currently enrolled in its primary and pre-primary education program, at a cost of $36 per year per child. It has graduated more than 9 million children from its schools, and research shows that children from BRAC schools tend to perform better academically than those from government schools, despite the challenges they face growing up.

Of course, access and quality are perennial problems in education, and they intersect with health, nutrition, and livelihood issues. The complexity of these interconnected problems pushed BRAC to expand its role over time; today, it intervenes at every point along the education value chain. For example, its advocacy work and body of evidence over many years persuaded the national government to provide pre-primary school for poor children. It opened BRAC Universityin 2001 to expand the nation's pipeline of talent: Today, this full-fledged higher-education institution enrolls some 6,000 students and has 22 departments, centers, and institutes. Within the university, BRAC has also created the Institute for Educational Development, which incubates new ideas and educational policies to further strengthen both government and private schools.

This education work is one example of achieving impact at scale. BRAC's Targeting the Ultra Poor program illustrates a different pathway: achieving significant impact by enlisting others and "giving away" the program. Since 2002, BRAC has helped 1.4 million families with a tailored approach to the problem of ultra-poverty, a form of dire poverty impervious to basic microfinance. The two-year "graduation" model involves cash stipends, livelihood training, asset transfer, access to savings, and other forms of social and emotional support—all used in combination as a springboard to better life. Though this approach is not a panacea, it has been highly effective, and as a result we now believe that there may finally be an end in sight for ultra-poverty.

For this program, we didn't just scale up directly—although direct implementation is important for knowledge and credibility. Instead, we chose to open-source the idea and give away its implementation knowledge to interested parties. Through patient participation in building a global community of practice, BRAC and BRAC University positioned the graduation idea to scale across borders and find the communities that could best benefit from it.

For example, intrigued by the powerful evidence from this program, the Ford Foundation and the Consultative Group to Assist the Poor (CGAP) launched a global experiment in 2006 to test the model in eight other countries, implemented by organizations other than BRAC. At a recent global gathering at the World Bank, we presented the research findings to policymakers, practitioners, and academics interested in ending extreme poverty. The overwhelming conclusion is that the approach works. Not only did 75 percent to 98 percent of households "graduate," but also the vast majority stayed out of extreme poverty.

In light of these results, we're redoubling our efforts to encourage others to "crowd in." We are inviting policymakers, funders, microfinance institutions, NGOs, academics, media, and others into the space, because all of these groups are critical to building and sustaining the social change movements essential for tackling extreme poverty.

BRAC may be big in the nonprofit world, but extreme poverty is much bigger. Matching the scale of solutions with the scale of global problems requires that we do more than just grow institutions and programs. Disciplined program development is an important part of effective scaling, but we also need to harness the power of social movements, and encourage and support the many others who have a stake in truly transformative change.