This book elaborates on a multidimensional model of decision-making that applies to how individuals make ""mundane decisions"" - decisions about pursuing relationships, exercise, work, or anything where people might have to ""invest"" time or behavioral effort are examples. The author utilizes cognitive-developmental theory to understand how children and adolescents make sense of economic inequality. This modern portfolio theory model of decision-making applies economic concepts to everyday life and may help us understand why individuals differ in their willingness to take risks. It also contributes to our knowledge of personality disorders such as depression and mania.