556distributed among children in different countries (Wold) and ask whether such measurements are valid and what influence them across cultures and countries (Trommsdorff). We continue by on a broad base to single out what affects the experience of well-being generally and among children and adolescents particularly. The issues covered are evolution (Grinde), genes (Nes), cognition (Thimm and Wang), personality (Torgersen and Waaktaar), family (Bowes and Bekkhus), transfer of values between parents and child (Headey, Muffels and Wagner), play (Borge), peer relations (Borge), kindergarten (Zachrisson and Lekhal), and school (Barry). We end the chapter by presenting five ways to practically enhance happiness in everyday life (Nes and Marks) and by guiding you through the world's largest database on happiness the World Database of Happiness (Veenhoven).Subjective well-being (SWB) is one of the most prominent topics in the study of positive mental health and attracts increasingly more attention in psychology, in particular in the branch of positive psychology. Positive psychology was introduced as a new area of psychology in 1998, when Martin Seligman chose it as the theme for his term as president of the American Psychological Association. According to Seligman (2002b, p. 3), "The aim of positive psychology is to catalyse a change in psychology from a preoccupation only with repairing the worst things in life to also building the best qualities in life." The first Handbook of Positive Psychology (Snyder and Lopez 2002) emerged in 2002, identifying several broad topics to be studied in positive psychology, such as identifying human strengths, fostering wellbeing, resilience, prosocial behavior, and quality of life (QOL). In this perspective, strategies and techniques for enhancing the well-being are educational, relational, social, and political interventions, not clinical treatments.An important task in positive psychology is to get insights into well-being and QOL in terms of three overlapping paths or pursuits: (1) the pleasant life, or the "life of enjoyment," how people optimally experience, forecast, and savor the positive feelings and emotions that are part of normal and healthy living (e.g., relationships, hobbies, interests, and entertainment); (2) the good life, or the "life of engagement," the beneficial effects of immersion, absorption, and flow that individuals feel when optimally engaged with their primary activities; and (3) the meaningful life, or "life of affiliation," how individuals derive a positive sense of well-being, belonging, meaning, and purpose from being part of and contributing back to something larger and more permanent than themselves (e.g., nature, social groups, organizations, movements, traditions, belief systems).Among children, the three paths are present in many areas of life, and play is among the most evident. Playing is for children and positive psychology seeks to 557 the early 1980s, Veenhoven (1984) attempted to solve the puzzle by including both hedonic level and contentmen...