To protect power generation, transmission, and distribution, energy companies need to control physical and logical access to their resources, including buildings, equipment, information technology (IT), and operational technology (OT). They must authenticate authorized individuals to the devices and facilities to which the companies are giving access rights with a high degree of certainty. In addition, they need to enforce access-control policies (e.g., allow, deny, inquire further) consistently, uniformly, and quickly across all of their resources. This project resulted from direct dialog among NCCoE staff and members of the electricity subsector, mainly from electric power companies and those who provide equipment and/or services to them. The goal of this project is to demonstrate a converged, standards-based technical approach that unifies identity and access management (IdAM) functions across OT networks, physical access control systems (PACS), and IT systems. These networks often operate independently, which can result in identity and access information disparity, increased costs, inefficiencies, and a loss of capacity and service delivery capability. Also, these networks support different infrastructures, each with unique security risks. The converged IdAM solution must be constructed to effectively address the highest-risk infrastructure. This guide describes our collaborative efforts with technology providers and electric-company stakeholders to address the security challenges that energy providers face in the core function of IdAM. This guide offers a technical approach to meeting the challenge and also incorporates a business-value mindset by identifying the strategic considerations involved in implementing new technologies. This NIST Cybersecurity Practice Guide provides a modular, open, end-to-end example solution that can be tailored and implemented by energy providers of varying sizes and levels of IT sophistication. It shows energy providers how we met the challenge by using open-source and commercially available tools and technologies that are consistent with cybersecurity standards. The use-case scenario is based on a normal day-to-day business operational scenario that provides the underlying impetus for the functionality presented in this guide. While the reference solution was demonstrated with a certain suite of products, this guide does not endorse these specific products. Instead, this guide presents the characteristics and capabilities that an organization’s security experts can use to identify similar standards-based products that can be integrated quickly and cost-effectively with an energy provider’s existing tools and infrastructure.