The Joint Capabilities Integration and Development System (JCIDS) was established in 2003 to overcome several shortcomings in the existing requirements process. Among other things, JCIDS introduced the notion of a "Capabilities-Based Assessment" (CBA) as the starting point in identifying the DoD's needs and recommending solutions. This document offers practical advice on how to conduct such an assessment. Since the original version of this guide was published in January 2006, JCIDS instructions and manuals have been revised several times, and many CBAs have been done by various organizations. This update addresses both the regulatory changes and what we have learned about doing these analyses. This guide does three things: first, it advises an action officer on how to organize and execute a CBA; second, it connects the CBA process to both the overarching strategic guidance and the proven analytical methods available in the DoD; and third, it uses an informal, readable style. As a result, this paper discusses bureaucratic realities that would not be addressed in an instruction, points out the occasional area where strategic guidance is immature, inconsistent, or conflicting, and aims at engaging the reader. This guide will provide you with a great deal of advice on how to assemble an assessment that meets the aims of JCIDS. While the guide is not directive or prescriptive, it captures important lessons from the CBAs conducted to date, and discusses the techniques and practices that have worked. Doing a good CBA is difficult, and this guide will not change that. But, a CBA should not be mystifying, and this paper is aimed at demystifying the inputs, best practices, and desired outcomes of such an assessment.