Book excerpt: This volume offers practical guidance on writing and preparing a description of government requirements, whether the document used is a statement of work (SOW), a performance work statement (PWS), or a statement of objectives (SOO). This description specifies exactly what good and services are being purchased, including their quality, requirements, quantity, and schedule for delivery, and also defines the relationship between the government and the contractor. From an overview of the elements that make a good SOW, to the methods for changing an SOW to meet new conditions, this is a hands-on resource for every government manager who is involved with contracts.