The topics discussed in this resource book include not only how to assess the long-term impact of early childhood Title I programs, but also how to develop and use a longitudinal information system for a variety of routine operations. The book is designed to help evaluators decide what a particular information system should look like. For longitudinal data to be useful, they must be collected and maintained systematically. That means: (1) data collection is done at regular intervals; (2) the population on whom data are collected remains the same; and (3) the data are filed in such a way that they can be easily obtained when they are needed. This resource book contains four chapters. In the first, two ways in which longitudinal information systems can be used are described (assessing long-term program impact, and helping with routine operations). The two main types of such systems are discussed in the second chapter, together with their strengths and weaknesses. Chapter 3 describes how to determine information needs, and Chapter 4 discusses different design features of systems that must be anticipated before building them. (Author/GK)