In 1912, a teacher in the one-room schoolhouse outside Stonewall, Texas, made a decision that would ultimately lead to billions of dollars in federal investment, volumes of research, and ongoing, decades-long debate about the value of early childhood education.

The teacher agreed to admit a 4-year-old boy who would go on to become President Lyndon Johnson.

As president, Johnson elevated the work of reducing poverty to a national priority—and giving the nation's poor children early opportunities to learn ranked among his top policy goals. "You have to understand that Johnson had been a teacher," says Joseph Califano Jr., a Johnson adviser and former secretary of Health, Education, and Welfare. "He was well aware of the vast differences in the way a Mexican-American child typically grew up in South Texas and a white, wealthy child lived on the Upper East side of Manhattan."

The result was a nationwide focus on early childhood and efforts to level the playing field for less-affluent children—particularly in urban areas so that poor children would no longer arrive at school with learning deficits. Ambitious policy programs like the Great Society and the War on Poverty led to experimental interventions like Head Start and Sesame Street. 50 years later, we have a much better understanding of the childhood skills and environments that can lead to success later in life. Even so, many questions remain shrouded in dispute and debate.

Big Bird and ABCs

From their very beginnings, preschool programs were developed specifically as interventions to help lower-income children. One of the first known preschools was established in London in 1910 to address the social, emotional, and intellectual needs of poor, urban children—and, advocates hoped, inculcate them with a sense of morality and values. Around the same time, Maria Montessori was working with poor children in Rome to hone her theories on child-driven, self-motivated learning.

Researchers in the U.S. really began to focus on some of the vast learning gaps between poor and wealthy kids in the 1950s, says Jane Waldfogel, a professor of social work and public affairs at Columbia University. Educational psychologists like Benjamin Bloom and J. McVicker Hunt published groundbreaking work based on longitudinal studies that confirmed the malleability of children in their earliest years. Child experts also gained valuable insights on the importance of quality early parenting when the World Health Organization commissioned British psychiatrist John Bowlby to study the mental health of orphaned children in Europe after World War II.

Suddenly, early childhood intervention looked like a potential weapon in the war on poverty. If cognition was not set, but could be developed, then even children born into families and communities with few resources could potentially gain skills early on that would improve their lives as adults. This new research provided much of the justification for the Head Start program—which began as a summer pilot project in 1965 and expanded to year-round shortly thereafter—as well as the federal government's decision to provide half of the original $8 million needed to launch the public television show Sesame Street when it premiered in 1969. Both interventions were targeted at low-income preschoolers, with the goal of reducing the learning gap by the time they started kindergarten.

Sharp debates over the goals of early childhood programs, and who the providers and recipients of this federally funded education should be, surrounded Head Start at the beginning—as they still do 50 years later. Head Start supporters also worried that Sesame Street might lead parents and policymakers to decide that television could be a replacement for early classroom learning.

It wasn't long, however, before researchers turned their attention to studying whether these interventions were producing the desired results. The Educational Testing Service conducted two evaluations in the early 1970s that indicated Sesame Street had a significant educational impact on kids who watched regularly, particular children from non-English-speaking homes. In fact, children from low-income homes who watched the program scored higher on letter-recognition and other language skills than children from high-income homes who were not regular viewers.

The results from Head Start were more mixed. By the early 1980s, studies started showing that the short-term IQ gains from Head Start education could fade away by the time a child reached third or fourth grade. However, there were benefits to Head Start participation that didn't show up on achievement tests—and those appeared promising. Head Start students ended up being held back less often when they moved onto elementary and middle school, and they had fewer referrals for special education.

The Importance of Social and Emotional Skills

Then, in 1994, the publication of The Bell Curve threw a grenade into debates over early childhood interventions. The book, written by psychologist Richard Hernnstein and political scientist Charles Murray, argued that ability and intellect are genetically determined. Suddenly the old nature-versus-nurture debate, which had been mostly dormant for several decades, roared back—and it attracted the research interest of University of Chicago economist James Heckman, who was just a few years away from winning the Nobel Prize for his work on econometrics.

Once Heckman started looking into early childhood interventions, he realized that assessments needed to include non-cognitive outcomes—the ability to self-motivate, exhibit self-control, and work toward long-term goals. Those social and emotional skills could influence whether a child later got involved in crime, stayed in high school, or was responsible for a teen pregnancy.

This insight—that teaching children how to learn can be just as important as the content of what they learn—has been one of two key developments in the area of early interventions. The other is a recognition that children are only part of the equation. As a National Academy of Sciences committee recounted in its report, "From Neurons to Neighborhoods: The Science of Early Childhood Development," "the field of early childhood intervention evolved from its original focus on children to a growing appreciation of the extent to which family, community, and broader societal factors affect child health and development." The more recent interest in home visit programs that can improve parenting skills and potentially alter home environments reflects this more holistic approach to improving children's opportunities.

New Investments in Early Interventions

Over the past two decades, Heckman has developed a case for investing in early interventions focused on low-income children and their families—and he has called for "a major refocus of policy … to capitalize on knowledge about the importance of the early years in creating inequality and in producing skills for the workforce." His research has been hailed, particularly by Democratic policymakers, in large part because Heckman makes the argument that money spent on early childhood intervention produces much higher economic returns than any later efforts in secondary education, job training, and certainly convict rehabilitation.

In its push for universal pre-K, the Obama administration has embraced Heckman's research. Critics, and even some sympathetic researchers, still warn that early childhood gains can dissipate unless they are reinforced by subsequent interventions. And congressional Republicans remain leery of a major new federal effort. But at a time when even Georgia and Oklahoma, two deep-red states, are funding expanded pre-K as a way of preventing much larger costs down the road, bolstering very young children might be one of the few policy initiatives with the potential to break the endemic standoff between the parties.

When President Johnson signed the bill authorizing Head Start back in 1965, he had some research to back up the idea of early childhood interventions—and a lot of hunches. Nearly half a century later, researchers have the benefit of long-term studies to give them more answers, although that hasn't ended debates on the subject.

It seems clear that the most effective efforts to help low-income children get an early start go beyond teaching numbers and letters—they involve the family, community, everything. Everything is expensive. But the kind of class-based achievement gap that led Johnson to fight for Head Start in the first place may be a cost the U.S. can't afford to pay as kids of color, many of them from families of modest means, become a majority of the future student population and workforce.