Locus of control (LOC) refers to the connections individuals perceive between their behavior and what happens to them. If they perceive such connections they are internally controlled; but if they see their outcomes as due to luck, fate or chance they are externally controlled. Even though researchers have found an internal LOC to be related positively to important aspects of human life including academic achievement, business success, physical and mental health and, in a United Nations study of 84 countries, to happiness, little is known about how internal and external LOC develop, their stability over time or whether they can be changed. Such information is important because over the past 30 years the average locus of control score for adults and children has become more external. We need to know why, and how to change that negative trend. The data to be used in this project include measures of LOC of parents during pregnancy and 16 years later, and of their children at ages 8 and 18 on over 12000 families. It is the only large study in the world that includes multiple assessments of LOC for children and their parents linked to relevant outcome measures. Statistical analyses will provide crucial information on how to foster internality and hence develop interventions.