The purpose of this National Critical Infrastructure Security and Resilience Research and Development Plan (hereafter referred to as the National CISR R&D Plan or the Plan) is to identify National R&D Priority Areas that inform R&D investments, promote innovation, and guide research activities across the critical infrastructure community. The critical infrastructure community includes public and private critical infrastructure owners and operators; Federal departments and agencies, including SSAs; State, local, tribal, and territorial (SLTT) governments and regional entities; and other organizations from the private and nonprofit sectors, including research and educational institutions and, in some cases, international partners and organizations. Future CISR R&D activities should be driven by continued collaborative efforts aimed at strengthening the security and resilience of critical infrastructure.