The National Nuclear Security Administration (NNSA) established a Nonproliferation Assessment Methodology (NPAM) Working Group, comprised of representatives from the Department of Energy (DOE) laboratories and academia, to develop guidelines for the practical application of Nonproliferation Assessment Methodologies (NPAM). The purpose of these methodologies is to address questions and issues related to the proliferation of nuclear weapons and weapons-useable nuclear materials and related technologies, as input to policy analysis. This document presents the guidelines developed by the Working Group.