Architectural metal roofing systems (AMRS) are considered to be a very durable type of steep-slope roofing system. Architectural metal roofing systems are commonly used in compact or unvented roofing assemblies over moisture-susceptible, nailable wood-based substrates placed directly over or laminated to rigid insulation or over nailable roof decks with spray-applied air- and vapor-impermeable polyurethane foam (SPUF) insulation applied directly to the underside of the deck. Use of AMRS without ventilation to relieve trapped moisture within the compact roofing assembly is commonplace, but under certain conditions, this practice can be risky. As is the case with most roofing systems, water trapped within roofing systems can lead to problems such as corrosion of fasteners and degradation of the substrate and supporting structural elements. Potential sources of water or moisture intrusion are many and can include intrusion of warm, humidified indoor air into the roofing system and condensation on cold surfaces, water leakage through the roofing system, or water entry during construction. Without adequate ventilation to relieve moisture, water trapped in the system can quickly cause damage to the underlying materials in the roof system. Ventilation of roofs over uninsulated decks and attic space is straightforward and commonly practiced, particularly when asphalt shingles are used. However, compact roof assemblies and assemblies with insulation above the deck require more sophisticated solutions that consider airflow continuity, placement of air and vapor retarders, and an understanding of the hygroscopic performance of the roofing system. This paper examines what makes architectural metal panel roof systems different from other systems in terms of construction techniques and moisture management, and it presents case studies and computer-based modeling of moisture flow to illustrate the need for ventilation. The authors discuss factors that increase the risk of moisture problems in AMRS and present effective design methods for ventilating and mitigating moisture in these roofing systems. Adequate protection of these systems from the effects of internal moisture using proper ventilation can help provide a robust, durable, and resilient AMRS.