In this book,we introduce the Generalized Container Loading Problem (GCLP) to model a more practical container loading issue. In this problem, we are given a set of three-dimensional containers and several sets of three-dimensional items. Each set of items can be further divided into two groups: mandatory items and optional items. Each container has a cost and each item has a value. We need to select one set of items and load all of its mandatory items,together with some or all of its optional items,into the container(s), such that the unit shipping cost is minimized. The unit shipping cost is defined as the quotient of the total cost of selected containers and the total value of loaded items. This problem successfully describes the multi-layer decision-making process and the trade-off between cost and value, which are common issues in logistics management.