This document defines and discusses collection development in school libraries. It explains that collection development is a process that involves developing a selection policy, evaluating existing collections, identifying new resources, and maintaining a collection that meets the diverse needs of students, teachers, and administrators. The key aspects of collection development outlined are developing a selection policy with goals, responsibilities, criteria for evaluating resources, and procedures for handling controversial materials. It also discusses ongoing collection maintenance activities like weeding and replacing old materials. The overall goal of collection development is to support teaching and learning by providing access to information in a variety of formats.