Second, when evaluating skill enhancement programmes it is vital to consider outcomes other than IQ or achievement test scores. Only interventions that start long before kindergarten begins have been shown to have long-term effects on IQ. If IQ were the only measure of success, most intervention programmes would seem futile. Using a diverse set of outcomes presents a more optimistic point of view. Many early programmes improve later-life outcomes, even though they do not improve IQ. These programmes work because they foster non-cognitive skills. Some have annual rates of return that are comparable to those from investments in the stock market. Parental involvement is an important component of successful early interventions just as successful adolescent mentoring is an age-appropriate version of parental involvement. The most promising adolescent programmes integrate aspects of work into traditional education. Such programmes break down the rigid separation between school and work that characterises the American high school. In addition, a nascent literature reports substantial benefits from giving information to adolescents. The apparent success of apprenticeship programmes might arise in part from their cultivation of non- cognitive skills. The attachment of a supervisor to an apprentice helps create non- cognitive skills in a version of the attachment bond between parent and child.6 The Perry intervention provides an effective rebuttal to these arguments. The programme greatly improved outcomes for both participating boys and girls, resulting in a statistically significant rate of return around 7%-10% per annum for both genders (see Heckman et al., 2010a). These returns are in the range of the post-World War II, pre-2008 meltdown stock market returns to equity in the U.S. labour market, estimated to be 6.9% per annum.13